Zoom lens system

ABSTRACT

Object is to provide an inner-focusing type zoom lens system carrying out focusing by moving a portion of a first lens group suitable for an auto-focus SLR camera. A zoom lens system includes, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, a distance between the first and the second lens groups increases, and a distance between the second and the third lens groups decreases. The first lens group is composed of, in order from the object, a 1A lens group G1A having positive refractive power, and a 1B lens group G1B having positive refractive power. Focusing from infinity to a close-range object is carried out by moving only the 1B lens group G1B to the object.

The disclosure of the following priority applications are hereinincorporated by reference:

-   -   Japanese Patent Application No. 2004-099773 filed on Mar. 30,        2004,    -   Japanese Patent Application No. 2004-105319 filed on Mar. 31,        2004,    -   Japanese Patent Application No. 2005-036624 filed on Feb. 14,        2005 and    -   Japanese Patent Application No. 2005-036633 filed on Feb. 14,        2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system suitable for asingle-lens-reflex (SLR) camera using a silver-halide film or asolid-state imaging device and in particular to an internal-focusingzoom lens system capable of focusing by moving a portion of the opticalsystem in a first lens group and also in particular to a compact zoomlens system having a vibration reduction function with a zoom ratio ofabout four and an angle of view of about 22° or more in a wide-angle endstate.

2. Related Background Art

As a conventional focusing method for a zoom lens, a front-lens-groupfocusing carrying out by moving the most object side lens group to theobject has been generally known. This method has a merit that the movingamount for focusing is determined in accordance with the object distanceregardless of the zooming position, so that it is effective forsimplifying the focusing mechanism. This method makes it possible toconstruct a first lens group with about three lens elements, so that itis effective for simplifying the construction of the lens system andlowering the manufacturing cost. However, since the moving lens groupfor focusing is exposed outside, when unexpected force is applied to thelens system, the focusing mechanism, in particular an auto-focusingmechanism, may be damaged. On the other hand, zoom lens systems with aninternal focusing method, in which focusing is carried out by a lensgroup other than the first lens group, have been proposed in largenumbers. However, it also has a problem that the moving amount forfocusing largely varies in accordance with the zoom position.

In order to solve the problems, a focusing method, in which the firstlens group is composed of a front lens group having positive refractivepower and a rear lens group having positive refractive power andfocusing is carried out by moving the rear lens group to the object, hasbeen proposed in Japanese Patent Application Laid-Open Nos. 6-51202,2000-19398, and 2000-284174.

However, although each example disclosed by Japanese Patent ApplicationLaid-Open No. 6-51202 constructing the first lens group by three lenselements as a whole, two lens elements in the front lens group and onelens element in the rear lens group, is suitable for simplifying theconstruction and lowering the manufacturing cost, since focusing iscarried out by moving only a single lens element with positiverefractive power, spherical aberration, on-axis chromatic aberration andlateral chromatic aberration becomes large upon focusing a close-rangeobject, so that it is undesirable for obtaining high opticalperformance.

Moreover, each example disclosed by Japanese Patent ApplicationLaid-Open No. 2000-19398 requires five lens elements in the first lensgroup, three lens elements in the front lens group and two lens elementsin the rear lens group, so that it is not suitable for simplifying theconstruction or lowering the manufacturing cost.

Furthermore, each example disclosed by Japanese Patent ApplicationLaid-Open No. 2000-284174 requires four lens elements in the first lensgroup, one lens element in the front lens group and three lens elementsin the rear lens group, so that it is not suitable for simplifying theconstruction or lowering the manufacturing cost.

Moreover, telephoto zoom lenses with a vibration reduction mechanismhaving a zoom ratio of about four have been proposed in Japanese PatentApplication Laid-Open Nos. 8-62541 and 10-133114.

Examples disclosed in Japanese Patent Application Laid-Open No. 8-62541are a five-group zoom lens withpositive-negative-positeve-positeve-negative power arrangement or asix-group zoom lens withpositive-negative-positive-negative-positive-negative power arrangementmoving the second lens group having negative refractive power forvibration reduction. However, in these disclosures, since the effectivediameter of the second lens group is 25 mm or more, the vibrationreduction mechanism becomes large, so that it becomes difficult to makethe zoom lens system be compact.

Examples disclosed in Japanese Patent Application Laid-Open No.10-133114 are a five-group zoom lens withpositive-negative-negateve-positeve-negative power arrangement moving aportion of lens group in the fourth lens group having positiverefractive power for vibration reduction. However, in these disclosures,since the effective diameter of the vibration reduction lens group inthe fourth lens group is 25 mm or more, the vibration reductionmechanism becomes large, so that it becomes difficult to make the zoomlens system be compact.

SUMMARY OF THE INVENTION

The present invention is made in view of the aforementioned problems andhas an object to provide an internal focusing zoom lens system suitablefor an auto focus SLR camera using a silver-halide film or a solid-stateimaging device, carrying out focusing by moving a portion of a firstlens group, having a zoom ratio of about four and an angle of view of22° or more in the wide-angle end state, and suitable for simplifyingthe lens construction of the first lens group and lowering manufacturingcost without compromising compactness or high optical performance.

According to one aspect of the present invention, a zoom lens systemincludes, in order from an object, a first lens group having positiverefractive power, a second lens group having negative refractive power,and a third lens group having positive refractive power. When a state oflens group positions varies from a wide-angle end state to a telephotoend state, a distance between the first lens group and the second lensgroup increases, and a distance between the second lens group and thethird lens group decreases. The first lens group is composed of, inorder from the object, a 1A lens group having positive refractive power,and a 1B lens group having positive refractive power. Focusing frominfinity to a close-range object is carried out by moving only the 1Blens group to the object, and the following conditional expressions (1)through (4) are satisfied:1.55<f1/fw<2.20  (1)−0.55<f2/fw<−0.30  (2)2.0<f1A/f1B<4.0  (3)0.16<DAB/fw<0.30  (4)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f1 denotes the focal length of the first lensgroup, f2 denotes the focal length of the second lens group, f1A denotesthe focal length of the 1A lens group, f1B denotes the focal length ofthe 1B lens group, and DAB denotes the distance between the 1A lensgroup and the 1B lens group when the zoom lens system is focused oninfinity.

In one preferred embodiment of the present invention, when the state oflens group positions varies from the wide-angle end state to thetelephoto end state, the first lens group and the third lens grouppreferably move to the object.

In one preferred embodiment of the present invention, the zoom lenssystem further includes a fourth lens group having negative refractivepower to an image side of the third lens group. When the state of lensgroup positions varies from the wide-angle end state to the telephotoend state, a distance between the third lens group and the fourth lensgroup varies, and the following conditional expressions (5) through (7)are preferably satisfied:0.35<f3/fw<0.70  (5)−1.50<f4/fw <−0.70  (6)−0.10<(D34w−D34t)/fw<0.10  (7)where f3 denotes the focal length of the third lens group, f4 denotesthe focal length of the fourth lens group, D34w denotes the distancebetween the third lens group and the fourth lens group in the wide-angleend state, and D34t denotes the distance between the third lens groupand the fourth lens group in the telephoto end state.

In one preferred embodiment of the present invention, the 1A lens groupis composed of only one positive lens, the 1B lens group is composed of,in order from the object, a negative meniscus lens having a convexsurface facing to the object, and a positive lens having a convexsurface facing to the object, and the following conditional expressions(8) and (9) are preferably satisfied:50<ν1A  (8)35<ν1BP−ν1BN  (9)where ν1A denotes Abbe number of the positive lens in the 1A lens groupat d-line (λ=587.6 nm), ν1BP denotes Abbe number of the positive lens inthe 1B lens group G1B at d-line, and ν1BN denotes Abbe number of thenegative meniscus lens in the 1B lens group G1B at d-line.

In one preferred embodiment of the present invention, the negativemeniscus lens and the positive lens in the 1B lens group are preferablycemented with each other.

According to another aspect of the present invention, a zoom lens systemwith a vibration reduction mechanism includes, in order from an object,a first lens group having positive refractive power, a second lens grouphaving negative refractive power, a third lens group having positiverefractive power, and a fourth lens group having negative refractivepower. When a state of lens group positions varies from a wide-angle endstate to a telephoto end state, a distance between the first lens groupand the second lens group increases, a distance between the second lensgroup and the third lens group decreases, and a distance between thethird lens group and the fourth lens group varies. The fourth lens groupis composed of, in order from the object, a 41 lens group, a 42 lensgroup having negative refractive power, and a 43 lens group. At leastone of the 41 lens group and the 43 lens group has positive refractivepower. Image blur on an image plane caused by a camera shake is reducedby moving only the 42 lens group perpendicular to the optical axis.

In one preferred embodiment of the present invention, the followingconditional expression (10) is preferably satisfied:0.10<f42/f4<0.90  (10)where f4 denotes the focal length of the fourth lens group, and f42denotes the focal length of the 42 lens group.

In one preferred embodiment of the present invention, the followingconditional expressions (11) and (12) are preferably satisfied:−2.10<f4/fw<−0.70  (11)−2.10<(1/f41+1/f43)·f4<−0.40  (12)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f41 denotes the focal length of the 41 lens groupand f43 denotes the focal length of the 43 lens group.

In one preferred embodiment of the present invention, when the state oflens group positions varies from the wide-angle end state to thetelephoto end state, the first lens group, the third lens group, and thefourth lens group preferably move to the object.

In one preferred embodiment of the present invention, the 41 lens grouppreferably includes at least one positive lens, the 42 lens grouppreferably includes at least one positive lens and at least one negativelens, and the 43 lens group preferably includes at least one positivelens.

In one preferred embodiment of the present invention, the 41 lens groupincludes, in order from the object, a negative lens having a concavesurface facing to the image, and a positive lens having a convex surfacefacing to the object, and the following conditional expression (13) ispreferably satisfied:0.20<n41N−n41P  (13)where n41N denotes refractive index of the negative lens in the 41 lensgroup at d-line (λ=587.6 nm), and n41P denotes refractive index of thepositive lens in the 41 lens group at d-line.

In one preferred embodiment of the present invention, the 42 lens groupincludes, in order from the object, a positive lens having a convexsurface facing to the image, and a double concave negative lens, and thefollowing conditional expression (14) is preferably satisfied:10.0<ν42N−ν42P  (14)where ν42N denotes Abbe number of the double concave negative lens inthe 42 lens group at d-line (λ=587.6 nm), and ν42P denotes Abbe dumberof the positive lens in the 42 lens group at d-line.

In one preferred embodiment of the present invention, the zoom lenssystem preferably consists only of, in order from the object, the firstlens group, the second lens group, the third lens group, and the fourthlens group.

In one preferred embodiment of the present invention, a fifth lens grouphaving positive refractive power is preferably arranged to the imageside of the fourth lens group.

In one preferred embodiment of the present invention, focusing frominfinity to a close-range object is preferably carried out by moving thefirst lens group as a whole to the object.

In one preferred embodiment of the present invention, focusing frominfinity to a close-range object is carried out by moving the secondlens group as a whole to the object, and the following conditionalexpression (15) is preferably satisfied:−0.98<M2t<−0.80  (15)where M2t denotes the magnification of the second lens group in thetelephoto end state.

In one preferred embodiment of the present invention, the first lensgroup is composed of, in order from the object, a 1A lens group havingpositive refractive power, and a 1B lens group having positiverefractive power, and focusing from infinity to a close-range object ispreferably carried out by moving only the 1B lens group to the object.

According to another aspect of the present invention, a zoom lens systemwith a vibration reduction mechanism includes, in order from an object,a first lens group having positive refractive power, a second lens grouphaving negative refractive power, and a third lens group having positiverefractive power. When a state of lens group positions varies from awide-angle end state to a telephoto end state, a distance between thefirst lens group and the second lens group increases, and a distancebetween the second lens group and the third lens group decreases. Thethird lens group is composed of, in order from the object, a 31 lensgroup having positive refractive power, a 32 lens group having negativerefractive power, and a 33 lens group. Image blur on an image planecaused by a camera shake is reduced by moving only the 32 lens groupperpendicular to the optical axis.

In one preferred embodiment of the present invention, the followingconditional expressions (16) through (20) are preferably satisfied:1.40<f1/fw<2.00  (16)−0.53<f2/fw<−0.32  (17)0.35<f3/fw<0.65   (18)−2.00<f32/f3<−0.80  (19)−0.20<f3/f33<0.50  (20)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f1 denotes the focal length of the first lensgroup, f2 denotes the focal length of the second lens group, f3 denotesthe focal length of the third lens group, f32 denotes the focal lengthof the 32 lens group, and f33 denotes the focal length of the 33 lensgroup.

In one preferred embodiment of the present invention, when the state oflens group positions varies from the wide-angle end state to thetelephoto end state, the first lens group and the third lens grouppreferably move to the object.

In one preferred embodiment of the present invention, the 31 lens grouppreferably includes at least three positive lenses and at least onenegative lens, the 32 lens group preferably includes at least onepositive lens and at least one negative lens, and the 33 lens grouppreferably includes at least one positive lens and at least one negativelens.

In one preferred embodiment of the present invention, the 31 lens groupincludes, in order from the object, a double convex positive lens, afirst cemented lens constructed by a double convex positive lenscemented with a negative lens having a concave surface facing to theobject, a positive meniscus lens having a convex surface facing to theobject, and a second cemented lens, and the following conditionalexpressions (21) and (22) are preferably satisfied:0.20<n31N−n31P  (21)30.0<ν31P−ν31N  (22)where n31N denotes refractive index of the negative lens in the firstcemented lens at d-line (λ=587.6 nm), n31P denotes refractive index ofthe positive lens in the first cemented lens at d-line, ν31N denotesAbbe number of the negative lens in the first cemented lens at d-line,and ν31P denotes Abbe number of the positive lens in the first cementedlens at d-line.

In one preferred embodiment of the present invention, the 32 lens groupincludes, in order from the object, a positive lens having a convexsurface facing to the image, and a double concave negative lens, and thefollowing conditional expression (23) is preferably satisfied:10.0<ν32N−ν32P  (23)where ν32N denotes Abbe number of the double concave negative lens inthe 32 lens group at d-line (λ=587.6 nm), and ν32P denotes Abbe numberof the positive lens in the 32 lens group at d-line.

In one preferred embodiment of the present invention, the 32 lens groupis composed of, in order from the object, a cemented lens constructed bya positive lens having a convex surface facing to the image cementedwith a double concave negative lens, and the following conditionalexpression (24) is preferably satisfied:−2.00<(r32R+r32F)/(r32R−r32F)<−0.70  (24)where r32F denotes the radius of curvature of the object side surface ofthe positive lens in the 32 lens group, r32R denotes the radius ofcurvature of the image side surface of the double concave negative lensin the 32 lens group.

In one preferred embodiment of the present invention, the followingconditional expression (25) is preferably satisfied:0.40<r32S/f32<0.90  (25)where r32S denotes the radius of curvature of the cemented lens in the32 lens group, and f32 denotes the focal length of the 32 lens group.

In one preferred embodiment of the present invention, the zoom lenssystem preferably consists only of, in order from the object, the firstlens group, the second lens group, and the third lens group.

In one preferred embodiment of the present invention, the first lensgroup is composed of, in order from the object, a 1A lens group havingpositive refractive power, and a 1B lens group having positiverefractive power, focusing from infinity to a close-range object iscarried out by moving only the 1B lens group to the object, and thefollowing conditional expression (26) is preferably satisfied:1.70<f1A/f1B<4.00  (26)where f1A denotes the focal length of the 1A lens group and f1B denotesthe focal length of the 1B lens group.

Other features and advantages according to the present invention will bereadily understood from the detailed description of the preferredembodiments in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a sectional view of a zoom lens systemaccording to Example 1 of a first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 2A and 2B show various aberrations of the zoom lens systemaccording to Example 1 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively.

FIGS. 3A and 3B show various aberrations of the zoom lens systemaccording to Example 1 of the first embodiment in an intermediate focallength state upon focusing at infinity, and at a closest shootingdistance, respectively.

FIGS. 4A and 4B show various aberrations of the zoom lens systemaccording to Example 1 of the first embodiment in a telephoto end stateupon focusing at infinity, and at a closest shooting distance,respectively.

FIG. 5 is a diagram showing a sectional view of a zoom lens systemaccording to Example 2 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 6A and 6B show various aberrations of the zoom lens systemaccording to Example 2 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively.

FIGS. 7A and 7B show various aberrations of the zoom lens systemaccording to Example 2 of the first embodiment in an intermediate focallength state upon focusing at infinity, and at a closest shootingdistance, respectively.

FIGS. 8A and 8B show various aberrations of the zoom lens systemaccording to Example 2 of the first embodiment in a telephoto end stateupon focusing at infinity, and at a closest shooting distance,respectively.

FIG. 9 is a diagram showing a sectional view of a zoom lens systemaccording to Example 3 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 10A and 10B show various aberrations of the zoom lens systemaccording to Example 3 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively.

FIGS. 11A and 11B show various aberrations of the zoom lens systemaccording to Example 3 of the first embodiment in an intermediate focallength state upon focusing at infinity, and at a closest shootingdistance, respectively.

FIGS. 12A and 12B show various aberrations of the zoom lens systemaccording to Example 3 of the first embodiment in a telephoto end stateupon focusing at infinity, and at a closest shooting distance,respectively.

FIG. 13 is a diagram showing a sectional view of a zoom lens systemaccording to Example 4 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 14A and 14B show various aberrations of the zoom lens systemaccording to Example 4 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively.

FIGS. 15A and 15B show various aberrations of the zoom lens systemaccording to Example 4 of the first embodiment in an intermediate focallength state upon focusing at infinity, and at a closest shootingdistance, respectively.

FIGS. 16A and 16B show various aberrations of the zoom lens systemaccording to Example 4 of the first embodiment in a telephoto end stateupon focusing at infinity, and at a closest shooting distance,respectively.

FIG. 17 is a diagram showing a sectional view of a zoom lens systemaccording to Example 5 of a second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 18A and 18B show various aberrations of the zoom lens systemaccording to Example 5 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 19 shows various aberrations of the zoom lens system according toExample 5 of the second embodiment in an intermediate focal lengthstate. upon focusing at infinity.

FIGS. 20A and 20B show various aberrations of the zoom lens systemaccording to Example 5 of the second embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 21 is a diagram showing a sectional view of a zoom lens systemaccording to Example 6 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 22A and 22B show various aberrations of the zoom lens systemaccording to Example 6 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 23 shows various aberrations of the zoom lens system according toExample 6 of the second embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 24A and 24B show various aberrations of the zoom lens systemaccording to Example 6 of the second embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 25 is a diagram showing a sectional view of a zoom lens systemaccording to Example 7 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 26A and 26B show various aberrations of the zoom lens systemaccording to Example 7 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 27 shows various aberrations of the zoom lens system according toExample 7 of the second embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 28A and 28B show various aberrations of the zoom lens systemaccording to Example 7 of the second embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 29 is a diagram showing a sectional view of a zoom lens systemaccording to Example 8 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 30A and 30B show various aberrations of the zoom lens systemaccording to Example 8 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 31 shows various aberrations of the zoom lens system according toExample 8 of the second embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 32A and 32B show various aberrations of the zoom lens systemaccording to Example 8 of the second embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 33 is a diagram showing a sectional view of a zoom lens systemaccording to Example 9 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 34A and 34B show various aberrations of the zoom lens systemaccording to Example 9 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 35 shows various aberrations of the zoom lens system according toExample 9 of the second embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 36A and 36B show various aberrations of the zoom lens systemaccording to Example 9 of the second embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 37 is a diagram showing a sectional view of a zoom lens systemaccording to Example 10 of a third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 38A and 38B show various aberrations of the zoom lens systemaccording to Example 10 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 39 shows various aberrations of the zoom lens system according toExample 10 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 40A and 40B show various aberrations of the zoom lens systemaccording to Example 10 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 41 is a diagram showing a sectional view of a zoom lens systemaccording to Example 11 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 42A and 42B show various aberrations of the zoom lens systemaccording to Example 11 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 43 shows various aberrations of the zoom lens system according toExample 11 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 44A and 44B show various aberrations of the zoom lens systemaccording to Example 11 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 45 is a diagram showing a sectional view of a zoom lens systemaccording to Example 12 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 46A and 46B show various aberrations of the zoom lens systemaccording to Example 12 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 47 shows various aberrations of the zoom lens system according toExample 12 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 48A and 48B show various aberrations of the zoom lens systemaccording to Example 12 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 49 is a diagram showing a sectional view of a zoom lens systemaccording to Example 13 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 50A and 50B show various aberrations of the zoom lens systemaccording to Example 13 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 51 shows various aberrations of the zoom lens system according toExample 13 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 52A and 52B show various aberrations of the zoom lens systemaccording to Example 13 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 53 is a diagram showing a sectional view of a zoom lens systemaccording to Example 14 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 54A and 54B show various aberrations of the zoom lens systemaccording to Example 14 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 55 shows various aberrations of the zoom lens system according toExample 14 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 56A and 56B show various aberrations of the zoom lens systemaccording to Example 14 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 57 is a diagram showing a sectional view of a zoom lens systemaccording to Example 15 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 58A and 58B show various aberrations of the zoom lens systemaccording to Example 15 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 59 shows various aberrations of the zoom lens system according toExample 15 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 60A and 60B show various aberrations of the zoom lens systemaccording to Example 15 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

FIG. 61 is a diagram showing a sectional view of a zoom lens systemaccording to Example 16 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

FIGS. 62A and 62B show various aberrations of the zoom lens systemaccording to Example 16 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively.

FIG. 63 shows various aberrations of the zoom lens system according toExample 16 of the third embodiment in an intermediate focal length stateupon focusing at infinity.

FIGS. 64A and 64B show various aberrations of the zoom lens systemaccording to Example 16 of the third embodiment in a telephoto end stateupon focusing at infinity, and meridional lateral aberration at infinitywhen vibration reduction is carried out against rotation of 0.15°,respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

The zoom lens system according to the first embodiment of the presentinvention is composed of, in order from an object, a first lens grouphaving positive refractive power, a second lens group having negativerefractive power, and a third lens group having positive refractivepower. When a state of lens group positions varies from a wide-angle endstate to a telephoto end state, a distance between the first lens groupand the second lens group increases, and a distance between the secondlens group and the third lens group decreases.

The first lens group is composed of, in order from the object, a 1A lensgroup G1A having positive refractive power and a 1B lens group G1Bhaving positive refractive power. Focusing from infinity to a close-rangobject is carried out by moving only the 1B lens group G1B to theobject.

With this construction, it can be prevented to expose movable lens groupfor focusing, so that it is advantageous for auto focus. Moreover, bycomposing the first lens group of the 1A lens group G1A having positiverefractive power and the 1B lens group G1B having positive refractivepower, increase in the number of lens elements can be prevented andvariation in aberration upon focusing can be suppressed.

The zoom lens system according to the first embodiment of the presentinvention satisfies the following conditional expressions (1) through(4):1.55<f1/fw<2.20  (1)−0.55<f2/fw<−0.30  (2)2.0<f1A/f1B<4.0  (3)0.16<DAB/fw<0.30  (4)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f1 denotes the focal length of the first lensgroup, f2 denotes the focal length of the second lens group, f1A denotesthe focal length of the 1A lens group, f1B denotes the focal length ofthe 1B lens group, and DAB denotes the distance between the 1A lensgroup and the 1B lens group when the zoom lens system is focused oninfinity.

Conditional expression (1) defines an appropriate range of the focallength of the first lens group. When the ratio f1/fw is equal to orfalls below the lower limit of conditional expression (1), positiverefractive power of the first lens group becomes large, so that itbecomes difficult to satisfactorily correct aberrations with fewernumber of lens elements. On the other hand, when the ratio f1/fw isequal to or exceeds the upper limit of conditional expression (1), thetotal length of the zoom lens system becomes large, so that it isundesirable.

In order to secure the effect of the present invention, it is preferablethat the lower limit of conditional expression (1) is set to 1.60 andthe upper limit to 2.00.

Conditional expression (2) defines an appropriate range of the focallength of the second lens group. When the ratio f2/fw is equal to orexceeds the upper limit of conditional expression (2), negativerefractive power of the second lens group becomes large, so that itbecomes difficult to correct various aberrations. On the other hand,when the ratio f2/fw is equal to or falls below the lower limit ofconditional expression (2), the total length of the zoom lens systembecomes large, so that it is undesirable.

In order to fully secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (2) is set to−0.50 and the upper limit to −0.35.

Conditional expression (3) defines an appropriate range of the ratio ofthe focal length of the 1A lens group to that of the 1B lens group. Whenthe ratio f1A/f1B is equal to or exceeds the upper limit of conditionalexpression (3), positive refractive power of the 1B lens group becomesstrong, so that it takes larger number of lens elements in the 1B lensgroup to correct aberrations. On the other hand, when the ratio f1A/f1Bis equal to or falls below the lower limit of conditional expression(3), positive refractive power of the 1A lens group becomes strong, sothat it takes larger number of lens elements in the 1A lens group tocorrect aberrations.

In order to further secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (3) is set to2.20 and the upper limit to 3.85.

Conditional expression (4) defines an appropriate range of the distancebetween the 1A lens group G1A and the 1B lens group G1B. When the ratioDAB/fw is equal to or exceeds the upper limit of conditional expression(4), the diameter of the 1A lens group becomes large, so that it isundesirable. On the other hand, when the ratio DAB/fw is equal to orfalls below the lower limit of conditional expression (4), the air spacefor moving the 1B lens group upon focusing becomes narrow, so that itbecomes difficult to secure the closest shooting distance to besufficiently near.

In order to further secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (4) is set to0.18 and the upper limit to 0.25.

It is preferable that when the state of lens group positions varies fromthe wide-angle end state to the telephoto end state, the first lensgroup and the third lens group move to the object. In this construction,the total lens length of the zoom lens system in the wide-angle endstate can be compact.

Moreover, it may be possible to construct the zoom lens system byincluding a fourth lens group having negative refractive power to theimage side of the third lens group and varying the distance between thethird lens group and the fourth lens group upon zooming from thewide-angle end state to the telephoto end state. By arranging the fourthlens group having negative refractive power to the image side of thethird lens group, the zoom lens system becomes a telephoto type powerarrangement, so that it is effective to shorten the total lens length ofthe zoom lens system. Moreover, by varying the distance between thethird lens group and the fourth lens group, variation in astigmatism andcurvature of field can be suppressed.

In the zoom lens system according to the first embodiment of the presentinvention, it is preferable to satisfy the following conditionalexpressions (5) through (7):0.35<f3/fw<0.70  (5)−1.50<f4/fw<−0.70  (6)−0.10<(D34w−D34t)/fw<0.10  (7)where f3 denotes the focal length of the third lens group, f4 denotesthe focal length of the fourth lens group, D34w denotes the distancebetween the third lens group and the fourth lens group in the wide-angleend state, and D34t denotes the distance between the third lens groupand the fourth lens group in the telephoto end state.

Conditional expression (5) defines an appropriate range of the focallength of the third lens group. When the ratio f3/fw is equal to orfalls below the lower limit of conditional expression (5), positiverefractive power of the third lens group becomes strong, so that itbecomes difficult to correct various aberrations as well as sphericalaberration. On the other hand, when the ratio f2/fw is equal to orexceeds the upper limit of conditional expression (5), the total lengthof the zoom lens system becomes large, so that it is undesirable.

In order to further secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (5) is set to0.40 and the upper limit to 0.60.

Conditional expression (6) defines an appropriate range of the focallength of the fourth lens group. When the ratio f4/fw is equal to orexceeds the upper limit of conditional expression (6), negativerefractive power of the fourth lens group becomes strong, so that itbecomes difficult to correct coma and distortion. On the other hand,when the ratio f4/fw is equal to or falls below the lower limit ofconditional expression (6), negative refractive power of the fourth lensgroup becomes weak decreasing the effect of the telephoto type powerarrangement, so that it becomes difficult to make the total lens lengthbe compact.

In order to further secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (6) is set to−1.20 and the upper limit to −0.85.

Conditional expression (7) defines an appropriate range of differencebetween the distance from the third lens group to the fourth lens groupin the wide-angle end state and that in the telephoto end state. Whenthe ratio (D34w−D34t)/fw is equal to or falls below the lower limit ofconditional expression (7), or is equal to or exceeds the upper limit ofconditional expression (7), it becomes difficult to satisfactorilycorrect variation in astigmatism and curvature of field upon zooming.

In order to further secure the effect of the present invention, it ispreferable that the lower limit of conditional expression (7) is set to−0.05 and the upper limit to 0.05.

In order to suppress the number of lens elements in the first lens groupto be three it is preferable that the 1A lens group G1A is composed ofonly one positive lens element and the 1B lens group G1B is composed of,in order from the object, a negative meniscus lens having a convexsurface facing to the object and a positive lens having a convex surfacefacing to the object. The construction is effective to make the zoomlens system simple, compact, and cheep.

Since the focusing lens group, which is the 1B lens group G1B, iscomposed of a negative lens and a positive lens, it becomes possible tocorrect spherical aberration and chromatic aberration, so that variationin spherical aberration and chromatic aberration upon focusing can besuppressed.

In the zoom lens system according to the first embodiment of the presentinvention, it is preferable to satisfy the following conditionalexpressions (8) and (9):50<ν1A  (8)35<ν1 BP−ν1 BN  (9)where ν1A denotes Abbe number of the positive lens in the 1A lens groupG1A at d-line (λ=587.6 nm), ν1BP denotes Abbe number of the positivelens in the 1B lens group G1B at d-line, and ν1BN denotes Abbe number ofthe negative meniscus lens in the 1B lens group G1B at d-line.

Conditional expression (8) defines an appropriate range of Abbe numberof the positive lens consisting of the 1A lens group G1A. When the valueν1A is equal to or falls below the lower limit of conditional expression(8), variation in chromatic aberration upon focusing becomes large, sthat it is undesirable. In order to further secure the effect of thepresent invention, it is preferable that the lower limit of conditionalexpression (8) is set to 60.

Conditional expression (9) defines an appropriate range of differencebetween Abbe number of the positive lens and that of the negativemeniscus lens consisting of the 1B lens group G1B. When the valueν1BP−ν1BN is equal to or falls below the lower limit of conditionalexpression (9), variation in chromatic aberration upon focusing andzooming becomes large, so that it is undesirable. In order to furthersecure the effect of the present invention, it is preferable that thelower limit of conditional expression (9) is set to 40.

Furthermore, it is preferable that the negative meniscus lens and thepositive lens in the 1B lens group are cemented. With this construction,degradation of optical performance or production of ghost images causedby assembling can be reduced.

Each example according to the first embodiment of the present inventionis explained with reference to accompanying drawings.

EXAMPLE 1

FIG. 1 is a diagram showing a sectional view of a zoom lens systemaccording to Example 1 of a first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming. In FIG. 1,the zoom lens system is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, an aperture stop S, a third lens groupG3 having positive refractive power, and a fourth lens group G4 havingnegative refractive power. When the state of lens group positions variesfrom a wide-angle end state (W) to a telephoto end state (T), the firstlens group G1, the third lens group G3, and the fourth lens group G4move to the object and the second lens group G2 moves once to the imageand, then, moves to the object such that a distance between the firstlens group G1 and the second lens group G2 increases, a distance betweenthe second lens group G2 and the third lens group G3 decreases, and adistance between the third lens group G3 and the fourth lens group G4varies. The aperture stop S moves together with the third lens group G3upon zooming from the wide-angle end state (W) to the telephoto endstate (T).

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. Focusing from infinity to aclose-range object is carried out by moving only the 1B lens group G1Bto the object.

The 1A lens group G1A is composed of a double convex positive lens L11.The 1B lens group G1B is composed of a cemented lens constructed by anegative meniscus lens L12 having a convex surface facing to the objectcemented with a double convex positive lens L13.

The second lens group G2 is composed of a double concave negative lens,a cemented lens constructed by a double concave negative lens cementedwith a double convex positive lens and a double concave negative lens.

The third lens group G3 is composed of a double convex positive lens, acemented lens constructed by a double convex positive lens cemented witha double concave negative lens, and a positive meniscus lens having aconvex surface facing to the object.

The fourth lens group G4 is composed of a cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens, a cemented lens constructedby a double convex positive lens cemented with a double concave negativelens, a double convex positive lens, and a negative meniscus lens havinga concave surface facing to the object.

Various values associated with Example 1 are listed in Table 1. In[Specifications], f denotes the focal length, FNO denotes the f-number,and 2ω denotes the angle of view. In [Lens Data], the first column isthe surface number counted in order from the object side, the secondcolumn r denotes the radius of curvature, the third column d denotes thedistance along the optical axis between the lens surfaces, and thefourth column ν denotes Abbe number at d-line (λ=587.6 nm) and the fifthcolumn n denotes refractive index at d-line (λ=587.6 nm). In the secondcolumn r, reference symbol “∞” denotes a plane. In the fifth column,refractive index of the air 1.00000 is omitted. In [Variable Distances],f denotes the focal length, M denotes the shooting magnification, D0denotes the distance between the object and the first lens surface, Rdenotes a distance between the object and the image plane, and Bfdenotes the back focal length. In [Values for Conditional Expressions],values for respective conditional expressions are shown.

In the tables for various values, “mm” is generally used for the unit oflength such as the focal length, the radius of curvature, and thedistance between optical surfaces. However, since an optical systemproportionally enlarged or reduced its dimension can be obtained similaroptical performance, the unit is not necessary to be limited to “mm” andany other suitable unit can be used. The explanation of referencesymbols is the same in the other examples and duplicated explanationsare omitted. TABLE 1 [Specifications] f = 71.40 135.20 294.00 FNO = 3.98  4.42  5.83 2ω = 34.26°  17.57°  8.19° [Lens Data] r d ν n 1401.1292 3.4320 64.14 1.516330 2 −401.1292 (d2) 3 73.7120 1.8000 28.461.728250 4 49.4588 9.2239 81.54 1.496999 5 −634.7712 (d5) 6 −569.62771.4000 46.57 1.804000 7 65.8130 2.9470 8 −66.3802 1.4000 49.34 1.7431989 37.4535 4.4348 23.78 1.846660 10 −157.1502 1.2424 11 −56.4033 1.400046.57 1.804000 12 457.6562 (d12) 13 ∞ 1.0000 Aperture Stop S 14 174.88834.0762 60.08 1.639999 15 −54.3627 0.2000 16 52.6528 6.0766 81.541.496999 17 −40.7675 1.4000 34.97 1.800999 18 1440.7843 0.2000 1933.5705 3.5534 61.13 1.589130 20 93.9894 (d20) 21 479.6438 1.4000 23.781.846660 22 43.7293 4.5629 59.84 1.522494 23 −51.1261 3.0000 241129.8061 3.6174 29.23 1.721507 25 −22.8122 1.4000 47.93 1.717004 2629.6916 4.4859 27 35.9110 3.4607 33.79 1.647689 28 −167.9338 4.3753 29−22.4279 1.4000 46.57 1.804000 30 −45.1019 (B.f.) Wide-angle endIntermediate Telephoto end [Variable Distances] (Infinity) f 71.40001135.19966 294.00012 D0 ∞ ∞ ∞ d2 13.96876 13.96876 13.96876 d5 1.5000030.16863 45.04078 d12 26.95417 16.63929 1.00000 d20 15.26706 15.2322516.01169 B.f. 45.82163 54.27048 80.82164 R ∞ ∞ ∞ (Closest ShootingDistance) M −0.05763 −0.11156 −0.24806 D0 1325.0000 1298.2322 1271.6687d2 1.45642 1.18529 0.90427 d5 14.01234 42.95210 58.10527 d12 26.9541716.63929 1.00000 d20 15.26706 15.23225 16.01169 B.f. 45.82163 54.2704880.82164 R 1500.0000 1500.0000 1500.0000 [Values for ConditionalExpressions] (1) f1/fw = 1.680 (2) f2/fw = −0.405 (3) f1A/f1B = 2.335(4) DAB/fw = 0.196 (5) f3/fw = 0.503 (6) f4/fw = −1.060 (7) (D34w −D34t) = −0.010 (8) ν1A = 64.14 (9) ν1BP − ν1BN = 53.08

FIGS. 2A and 2B show various aberrations of the zoom lens systemaccording to Example 1 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively. FIGS. 3A and 3B show various aberrations of the zoom lenssystem according to Example 1 of the first embodiment in an intermediatefocal length state upon focusing at infinity, and at a closest shootingdistance, respectively. FIGS. 4A and 4B show various aberrations of thezoom lens system according to Example 1 of the first embodiment in atelephoto end state upon focusing at infinity, and at a closest shootingdistance, respectively.

In respective graphs, FNO denotes the f-number, Y denotes an imageheight, and D, G denote aberration curves for d-line (λ=587.6 nm) andg-line (λ=435.8 nm), respectively. In graphs showing astigmatism, asolid line indicates a sagittal image plane, and a broken line indicatesa meridional image plane. In the following Examples, the same referencesymbols as Example 1 are used.

As is apparent from respective graphs, the zoom lens system according toExample 1 of the first embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 2

FIG. 5 is a diagram showing a sectional view of a zoom lens systemaccording to Example 2 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming. In FIG. 5,the zoom lens system is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, an aperture stop S, a third lens groupG3 having positive refractive power, and a fourth lens group G4 havingnegative refractive power. When the state of lens group positions variesfrom a wide-angle end state (W) to a telephoto end state (T), the firstlens group G1, the third lens group G3, and the fourth lens group G4move to the object and the second lens group G2 moves once to the imageI and, then, moves to the object such that a distance between the firstlens group G1 and the second lens group G2 increases, a distance betweenthe second lens group G2 and the third lens group G3 decreases, and adistance between the third lens group G3 and the fourth lens group G4varies. The aperture stop S moves together with the third lens group G3upon zooming from the wide-angle end state (W) to the telephoto endstate (T).

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. Focusing from infinity to aclose-range object is carried out by moving only the 1B lens group G1Bto the object.

The 1A lens group G1A is composed of a double convex positive lens L11.The 1B lens group G1B is composed of a cemented lens constructed by anegative meniscus lens L12 having a convex surface facing to the objectcemented with a double convex positive lens L13.

The second lens group G2 is composed of a double concave negative lens,a cemented lens constructed by a double concave negative lens cementedwith a double convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

The third lens group G3 is composed of a double convex positive lens, acemented lens constructed by a double convex positive lens cemented witha double concave negative lens, and a positive meniscus lens having aconvex surface facing to the object.

The fourth lens group G4 is composed of a cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens, a double convex positivelens, a double concave negative lens, a double convex positive lens, anda negative meniscus lens having a concave surface facing to the object.

Various values associated with Example 2 are listed in Table 2. TABLE 2[Specifications] f = 71.40 135.20 294.00 FNO =  3.92  4.34  5.79 2ω =34.01°  17.48°  8.17° [Lens Data] r d ν n 1 393.7797 3.4666 64.141.516330 2 −393.7797 (d2) 3 72.1379 1.8000 28.46 1.728250 4 48.59199.3212 81.54 1.496999 5 −673.5520 (d5) 6 −371.5827 1.4000 46.57 1.8040007 57.6115 3.0775 8 −66.8503 1.4000 49.34 1.743198 9 39.7971 4.4329 23.781.846660 10 −120.0368 1.3565 11 −48.2268 1.4000 46.57 1.804000 12−623.8156 (d12) 13 ∞ 1.0000 Aperture Stop S 14 171.0600 4.2202 60.081.639999 15 −51.8912 0.2000 16 53.6971 5.9454 81.54 1.496999 17 −42.44151.4000 34.97 1.800999 18 798.2716 0.2000 19 34.9966 3.3788 61.131.589130 20 91.1723 (d20) 21 224.4236 1.4000 23.78 1.846660 22 39.70383.2867 59.84 1.522494 23 −225.6684 6.3172 24 337.2025 3.1647 27.791.740769 25 −33.6532 0.2000 26 −34.9705 1.4000 46.57 1.804000 27 41.88823.6016 28 48.8184 3.6441 33.79 1.647689 29 −72.7425 10.5386 30 −22.26041.4000 46.57 1.804000 31 −42.1654 (B.f.) Wide-angle end IntermediateTelephoto end [Variable Distances] (Infinity) f 71.40227 135.19993294.00037 D0 ∞ ∞ ∞ d2 13.53509 13.53509 13.53509 d5 1.60134 30.0841144.43064 d12 26.58593 16.43870 1.00000 d20 14.32441 14.04027 14.43188B.f. 40.00116 48.12784 75.00135 R ∞ ∞ ∞ (Closest Shooting Distance) M−0.05757 −0.11137 −0.24756 D0 1325.0001 1298.8220 1272.6491 d2 1.429311.17314 0.90588 d5 13.70712 42.44606 57.05985 d12 26.58593 16.438701.00000 d20 14.32441 14.04027 14.43188 B.f. 40.00116 48.12784 75.00135 R1500.0000 1500.0000 1500.0000 [Values for Conditional Expressions] (1)f1/fw = 1.653 (2) f2/fw = −0.402 (3) f1A/f1B = 2.326 (4) DAB/fw = 0.190(5) f3/fw = 0.513 (6) f4/fw = −1.039 (7) (D34w − D34t) = −0.002 (8) ν1A= 64.14 (9) ν1BP − ν1BN = 53.08

FIGS. 6A and 6B show various aberrations of the zoom lens systemaccording to Example 2 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively. FIGS. 7A and 7B show various aberrations of the zoom lenssystem according to Example 2 of the first embodiment in an intermediatefocal length state upon focusing at infinity, and at a closest shootingdistance, respectively. FIGS. 8A and 8B show various aberrations of thezoom lens system according to Example 2 of the first embodiment in atelephoto end state upon focusing at infinity, and at a closest shootingdistance, respectively.

As is apparent from respective graphs, the zoom lens system according toExample 2 of the first embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 3

FIG. 9 is a diagram showing a sectional view of a zoom lens systemaccording to Example 3 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming. In FIG. 9,the zoom lens system is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, an aperture stop S, a third lens groupG3 having positive refractive power, and a fourth lens group G4 havingnegative refractive power. When the state of lens group positions variesfrom a wide-angle end state (W) to a telephoto end state (T), the firstlens group G1, the third lens group G3, and the fourth lens group G4move to the object and the second lens group G2 moves once to the imageI and, then, moves to the object such that a distance between the firstlens group G1 and the second lens group G2 increases, a distance betweenthe second lens group G2 and the third lens group G3 decreases, and adistance between the third lens group G3 and the fourth lens group G4varies. The aperture stop S moves together with the third lens group G3upon zooming from the wide-angle end state (W) to the telephoto endstate (T).

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. Focusing from infinity to aclose-range object is carried out by moving only the 1B lens group G1Bto the object.

The 1A lens group G1A is composed of a double convex positive lens L11.The 1B lens group GiB is composed of a cemented lens constructed by anegative meniscus lens L12 having a convex surface facing to the objectcemented with a double convex positive lens L13.

The second lens group G2 is composed of a double concave negative lens,a cemented lens constructed by a double concave negative lens cementedwith a double convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

The third lens group G3 is composed of a double convex positive lens, acemented lens constructed by a double convex positive lens cemented witha double concave negative lens, and a positive meniscus lens having aconvex surface facing to the object.

The fourth lens group G4 is composed of a cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens, a double convex positivelens a double concave negative lens, a double convex positive lens, anda negative meniscus lens having a concave surface facing to the object.

Various values associated with Example 3 are listed in Table 3. TABLE 3[Specifications] f = 71.40 134.90 294.00 FNO =  4.00  4.40  5.87 2ω =34.03°  17.50°  8.17° [Lens Data] r d ν n 1 14220.5510 2.7079 64.141.516330 2 −321.5792 (d2) 3 69.9601 1.8000 34.97 1.800999 4 46.37660.2000 5 45.9671 11.3706 81.54 1.496999 6 −419.6274 (d6) 7 −579.11681.4000 46.57 1.804000 8 63.8363 3.4452 9 −52.7313 1.4000 49.34 1.74319810 48.3987 4.2542 23.78 1.846660 11 −107.9428 0.8861 12 −61.0721 1.400046.57 1.804000 13 −623.8156 (d13) 14 ∞ 1.0000 Aperture Stop S 15166.9626 3.9296 60.08 1.639999 16 −58.2127 0.2000 17 57.0867 5.496781.54 1.496999 18 −46.6872 1.4000 34.97 1.800999 19 1396.9076 0.2000 2034.3256 3.4395 61.13 1.589130 21 91.8543 (d21) 22 203.1166 1.4000 23.781.846660 23 40.7958 3.2583 59.84 1.522494 24 −258.7153 7.3113 25302.9723 3.0588 27.79 1.740769 26 −35.3253 0.2000 27 −36.4959 1.400046.57 1.804000 28 40.5142 4.9030 29 51.7471 3.3861 33.79 1.647689 30−82.2838 9.1961 31 −22.3825 1.4000 46.57 1.804000 32 −41.2791 (B.f.)Wide-angle end Intermediate Telephoto end [Variable Distances](Infinity) f 71.39992 134.89970 293.99916 D0 ∞ ∞ ∞ d2 15.80731 15.8073115.80731 d6 1.50000 34.04735 50.19310 d13 29.37034 18.20055 1.00000 d2113.27877 12.96969 12.95602 B.f. 40.00001 47.68741 74.99998 R ∞ ∞ ∞(Closest Shooting Distance) M −0.05859 −0.11340 −0.25277 D0 1320.00001291.2441 1265.0000 d2 1.48390 1.14166 0.81459 d6 15.82341 48.7130065.18582 d13 29.37034 18.20055 1.00000 d21 13.27877 12.96969 12.95602B.f. 40.00001 47.68741 74.99998 R 1500.0000 1500.0000 1500.0000 [Valuesfor Conditional Expressions] (1) f1/fw = 1.823 (2) f2/fw = −0.449 (3)f1A/f1B = 3.778 (4) DAB/fw = 0.221 (5) f3/fw = 0.521 (6) f4/fw = −0.928(7) (D34w − D34t) = 0.005 (8) ν1A = 64.14 (9) ν1BP − ν1BN = 46.57

FIGS. 10A and 10B show various aberrations of the zoom lens systemaccording to Example 3 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively. FIGS. 11A and 11B show various aberrations of the zoomlens system according to Example 3 of the first embodiment in anintermediate focal length state upon focusing at infinity, and at aclosest shooting distance, respectively. FIGS. 12A and 12B show variousaberrations of the zoom lens system according to Example 3 of the firstembodiment in a telephoto end state upon focusing at infinity, and at aclosest shooting distance, respectively.

As is apparent from respective graphs, the zoom lens system according toExample 3 of the first embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 4

FIG. 13 is a diagram showing a sectional view of a zoom lens systemaccording to Example 4 of the first embodiment of the present inventiontogether with a trajectory of each lens group upon zooming. In FIG. 13,the zoom lens system is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, and a third lens group G3 havingpositive refractive power. When the state of lens group positions variesfrom a wide-angle end state (W) to a telephoto end state (T), the firstlens group G1 and the third lens group G3 move to the object and thesecond lens group G2 moves once to the image I and, then, moves to theobject such that a distance between the first lens group G1 and thesecond lens group G2 increases, and a distance between the second lensgroup G2 and the third lens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens L11. The 1B lens group G1B is composed of,in order from the object, a cemented lens constructed by a negativemeniscus lens L12 having a convex surface facing to the object cementedwith a double convex positive lens L13.

Focusing from infinity to a close-range object is carried out by movingonly the 1B lens group G1B to the object.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a negative meniscus lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingpositive refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with anegative meniscus lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, afixed stop S2, a double convex positive lens, and a negative meniscuslens having a concave surface facing to the object.

An aperture stop S is arranged to the object side of the 31 lens groupG31 and is moved together with the third lens group G3 upon zooming fromthe wide-angle end state (W) to the telephoto end state (T).

Various values associated with Example 4 is listed in Table 4. TABLE 4[Specifications] f = 71.40 135.00 294.00 FNO =  4.64  4.85  5.88 2ω =34.46°  17.55°  8.20° [Lens Data] r d ν n 1 340.6588 4.2 64.14 1.51633 2−340.659 (d2) 3 65.1639 1.8 26.3 1.784696 4 45.8381 8.8 81.61 1.496999 5−1308.92 (d5) 6 −271.25 1.4 49.61 1.772499 7 71.7854 1.3 8 −566.934 1.449.61 1.772499 9 24.4437 4.7 23.78 1.84666 10 133.0962 3.75 11 −46.09181.4 49.61 1.772499 12 1927.614 (d12) 13 ∞ 2 Aperture Stop S 14 188.67473.4 60.09 1.639999 15 −72.245 0.2 16 73.7218 6 81.61 1.496999 17−38.1983 1.4 34.96 1.800999 18 −154.661 0.2 19 32.255 4.2 52.42 1.51741720 143.854 7.9 21 333.5741 1.3 23.78 1.84666 22 54.3293 4.1 70.241.48749 23 −89.5707 10.2 24 256.9205 3.6 25.43 1.805181 25 −35.5686 1.239.59 1.804398 26 35.5686 3.4 27 ∞ 3.1 Fixed Stop S2 28 47.0802 4 34.471.639799 29 −96.8946 2.4 30 −23.3234 1.2 49.61 1.772499 31 −42.5579(B.f.) Wide-angle end Intermediate Telephoto end [Variable Distances](Infinity) f 71.39993 134.99982 294.00047 D0 ∞ ∞ ∞ d2 13.43865 13.4386513.43865 d5 2.49989 31.01849 43.01129 d12 28.21141 18.59271 2.50011 B.f.53.40008 57.30852 87.10064 R ∞ ∞ ∞ (Closest Shooting Distance) M−0.05775 −0.11125 −0.24755 D0 1313.9000 1291.0916 1265.3993 d2 2.362892.15893 1.91994 d5 13.57565 42.29821 54.53000 d12 28.21141 18.592712.50011 B.f. 53.40008 57.30852 87.10064 R 1500.0000 1500.0000 1500.0000[Values for Conditional Expressions] (1) f1/fw = 1.563 (2) f2/fw =−0.368 (3) f1A/f1B = 2.051 (4) DAB/fw = 0.188 (5) f3/fw = 0.525 (8) ν1A= 64.14 (9) ν1BP − ν1BN = 55.31

Wide-angle end Intermediate Telephoto end f 71.39993 134.99982 294.00047D0 ∞ ∞ ∞ d2 13.43865 13.43865 13.43865 d5 2.49989 31.01849 43.01129 d1228.21141 18.59271 2.50011 B.f. 53.40008 57.30852 87.10064 R ∞ ∞ ∞

FIGS. 14A and 14B show various aberrations of the zoom lens systemaccording to Example 4 of the first embodiment in a wide-angle end stateupon focusing at infinity, and at a closest shooting distance (1500 mm),respectively. FIGS. 15A and 15B show various aberrations of the zoomlens system according to Example 4 of the first embodiment in anintermediate focal length state upon focusing at infinity, and at aclosest shooting distance, respectively. FIGS. 16A and 16B show variousaberrations of the zoom lens system according to Example 4 of the firstembodiment in a telephoto end state upon focusing at infinity, and at aclosest shooting distance, respectively.

As is apparent from respective graphs, the zoom lens system according toExample 4 of the first embodiment shows superb optical performancecorrecting various aberrations.

Second Embodiment

A zoom lens system according to a second embodiment of the presentinvention is explained below.

The zoom lens system with a vibration reduction mechanism according tothe second embodiment of the present invention is composed of, in orderfrom an object, a first lens group having positive refractive power, asecond lens group having negative refractive power, a third lens grouphaving positive refractive power, and a fourth lens group havingnegative refractive power. When the state of lens group positions variesfrom a wide-angle end state to a telephoto end state, a distance betweenthe first lens group and the second lens group increases, a distancebetween the second lens group and the third lens group decreases, and adistance between the third lens group and fourth lens group varies. Theconstruction is effective for shortening the total lens length.

The fourth lens group is composed of, in order from the object, a 41lens group, a 42 lens group having negative refractive power, and a 43lens group.

At least one of the 41 lens group and the 43 lens group has positiverefractive power. By moving only the 42 lens group perpendicular to theoptical axis, image blur on an image plane caused by a camera shake canbe reduced.

With constructing the fourth lens group having negative refractivepower, the effective diameter of the fourth lens group can be smallrelative to those of the first lens group through the third lens group.Moreover, by constructing power arrangement of the fourth lens groupwith positive-negative-positive, positive-negative-negative, ornegative-negative-positive, the effective diameter of the 42 lens group,which is the vibration reduction lens group, can be small. Accordingly,the vibration reduction mechanism can be compact, so that it iseffective for the zoom lens system as a whole to be compact. Byconstructing in this manner, degradation of optical performance causedby moving the 42 lens group perpendicular to the optical axis can bereduced.

In the zoom lens system according to the second embodiment of thepresent invention, the following conditional expression (10) ispreferably satisfied:0.10<f42/f4<0.90  (10)where f4 denotes the focal length of the fourth lens group, and f42denotes the focal length of the 42 lens group.

Conditional expression (10) defines an appropriate range of the focallength of the 42 lens group suitable for vibration reduction. When theratio f42/f4 is equal to or exceeds the upper limit of conditionalexpression (10), negative refractive power of the 42 lens group becomesweak, so that an amount of decentering of the 42 lens required forvibration reduction becomes large. Accordingly, the vibration reductionmechanism becomes large, so that it becomes difficult to suppress thewhole dimension of the zoom lens system to be compact. On the otherhand, when the ratio f42/f4 is equal to or falls below the lower limitof conditional expression (10), negative refractive power of the 42 lensgroup becomes large. Accordingly, production of various aberrations inthe 42 lens group becomes large, so that production of decenteringaberration upon moving the 42 lens group for vibration reduction becomeslarge.

In order to further secure the effect of the present invention, it isdesirable to set the lower limit of conditional expression (10) to 0.25and the upper limit to 0.70.

In the zoom lens system according to the second embodiment of thepresent invention, the following conditional expressions (11) and (12)are preferably satisfied:−2.10<f4/fw<−0.70  (11)−2.10<(1/f41+1/f43)·f4<−0.40  (12)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f41 denotes the focal length of the 41 lens group,and f43 denotes the focal length of the 43 lens group.

Conditional expression (11) defines an appropriate range of the focallength of the fourth lens group suitable for miniaturizing the totallength of the zoom lens system and the effective diameter of the fourthlens group. When the ratio f4/fw is equal to or exceeds the upper limitof conditional expression (11), negative refractive power of the fourthlens group becomes excessively large, so that it becomes difficult tosatisfactorily correct aberrations. On the other hand, when the ratiof4/fw is equal to or falls below the lower limit of conditionalexpression (11), negative refractive power of the fourth lens groupbecomes small, so that it becomes difficult to miniaturize the totallength of the zoom lens system and the effective diameter of the fourthlens group.

In order to further secure the effect of the present invention, it isdesirable to set the lower limit of conditional expression (11) to −2.00and the upper limit to −0.90.

Conditional expression (12) defines an appropriate range of thesummation of refractive power of the 41 lens group and that of the 43lens group suitable for miniaturizing the effective diameter of the 42lens group. When the value (1/f41+1/f43)·f4 is equal to or falls belowthe lower limit of conditional expression (12), the summation ofrefractive power of the 41 lens group and that of the 43 lens groupbecomes large, so that negative refractive power of the 42 lens grouphas to be large in order to obtain negative refractive power of thefourth lens group as a whole. As a result, production of variousaberrations in the 42 lens group becomes large, so that production ofdecentering aberration caused by moving the 42 lens group for vibrationreduction becomes large. On the other hand, when the value(1/f41+1/f43)·f4 is equal to or exceeds the upper limit of conditionalexpression (12), the summation of refractive power of the 41 lens groupand that of the 43 lens group becomes small, so that the effect ofconverging the light flux becomes weak. As a result, miniaturizing theeffective diameter of the 42 lens group becomes insufficient.

In order to further secure the effect of the present invention, it isdesirable to set the lower limit of conditional expression (12) to −2.00and the upper limit to −0.50.

Moreover, the zoom lens system is preferably constructed such that whenthe state of lens group positions varies from the wide-angle end stateto the telephoto end state, the first lens group, the third lens group,and the fourth lens group are moved to the object side. With thisconstruction, the total lens length of the zoom lens system in thewide-angle end state can be compact.

Furthermore, it is preferable that the 41 lens group includes at leastone positive lens element, the 42 lens group includes at least onepositive lens element and at least one negative lens element, and the 43lens group includes at least one positive lens element. With thisconstruction, decentering aberration upon vibration reduction can becorrected well.

Furthermore, in the zoom lens system according to the second embodimentof the present invention, the 41 lens group includes, in order from theobject, a negative lens having a concave surface facing to the object, apositive lens having a convex surface facing to the object, and thefollowing conditional expression (13) is preferably satisfied:0.20<n41N−n41P  (13)where n41N denotes refractive index of the negative lens in the 41 lensgroup at d-line (λ=578.6 nm), and n41P denotes refractive index of thepositive lens in the 41 lens group at d-line.

Conditional expression (13) is for satisfactorily correcting decenteringaberration upon vibration reduction. When the value n41N−n41P is equalto or falls below the lower limit of conditional expression (13), itbecomes difficult to correct decentering aberration upon vibrationreduction. In order to further secure the effect of the presentinvention, it is desirable to set the lower limit of conditionalexpression (13) to 0.25.

In the zoom lens system according to the second embodiment of thepresent invention, the 42 lens group includes, in order from the object,a positive lens having a convex surface facing to the image, and adouble concave negative lens, and the following conditional expression(14) is preferably satisfied:10.0<ν42 N−ν42P  (14)where ν42N denotes Abbe number of the double concave negative lens inthe 42 lens group at d-line (λ=578.6 nm), and ν42P denotes Abbe numberof the positive lens in the 42 lens group at d-line.

Conditional expression (14) is for satisfactorily correcting decenteringaberrations upon vibration reduction. When the value ν42N−ν42P is equalto or falls below the lower limit of conditional expression (14), itbecomes difficult to correct lateral chromatic aberration produced bydecentering upon vibration reduction. In order to further secure theeffect of the present invention, it is desirable to set the lower limitof conditional expression (14) to 12.0.

In the zoom lens system according to the second embodiment of thepresent invention, it is preferable that the zoom lens system consistsonly of the first lens group, the second lens group, the third lensgroup, and the fourth lens group. By arranging no lens group withrefractive power to the image side of the fourth lens group, the zoomlens system can be simple.

In the zoom lens system according to the second embodiment of thepresent invention, it is preferable that a fifth lens group havingpositive refractive power is arranged to the image side of the fourthlens group. With this construction, the degree of freedom for correctingaberration increases, so that various aberrations can be correctedeasily.

Moreover, it is preferable that the first lens group as a whole is movedto the object upon focusing from infinity to a close-range object.

Furthermore, it is preferable that the second lens group as a whole ismoved to the object upon focusing from infinity to a close-range object,and the following conditional expression (15) is preferably satisfied:−0.98<M2t<−0.8  (15)where M2t denotes magnification of the second lens group in thetelephoto end state.

When the value M2t is equal to or falls below the lower limit ofconditional expression (15), the magnification becomes nearly to −1, sothat focusing cannot be carried out. On the other hand, when the valueM2t is equal to or exceeds the upper limit of conditional expression(15), it becomes difficult to obtain zoom ratio of about four. In orderto further secure the effect of the present invention, it is desirableto set the upper limit of conditional expression (15) to −0.90.

In the zoom lens system according to the second embodiment of thepresent invention, it is preferable that the first lens group iscomposed of, in order from the object, a 1A lens group G1A havingpositive refractive power, and a 1B lens group G1B having positiverefractive power, and focusing from infinity to a close-range object iscarried out by moving only the 1B lens group to the object.

Each example of the second embodiment is explained below with referenceto accompanying drawings.

EXAMPLE 5

FIG. 17 is a diagram showing a sectional view of a zoom lens systemaccording to Example 5 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 17, a zoom lens system with a vibration reduction mechanismaccording to Example 5 is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, a third lens group G3 having positiverefractive power, and a fourth lens group G4 having negative refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1, thethird lens group G3, and the fourth lens group G4 move to the object andthe second lens group G2 moves once to an image I and, then, moves tothe object such that a distance between the first lens group G1 and thesecond lens group G2 increases, a distance between the second lens groupG2 and the third lens group G3 decreases, and a distance between thethird lens group G3 and the fourth lens group G4 increases.

The first lens group G1 is composed of, in order from the object, acemented lens constructed by a negative meniscus lens having a convexsurface facing to the object cemented with a double convex positivelens, and a positive meniscus lens having a convex surface facing to theobject.

The second lens group G2 is composed of, in order from the object, acemented lens constructed by a positive meniscus lens having a concavesurface facing to the object cemented with a double concave negativelens, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, adouble convex positive lens, a cemented lens constructed by a doubleconvex positive lens cemented with a negative meniscus lens having aconcave surface facing to the object, and a positive meniscus lenshaving a convex surface facing to the object.

An aperture stop S is arranged between a double convex positive lens anda cemented lens in the third lens group G3 and is moved together withthe third lens group G3 upon zooming from the wide-angle end state (W)to the telephoto end state (T).

The fourth lens group G4 is composed of, in order from the object, a 41lens group G41 having negative refractive power, a 42 lens group G42having negative refractive power, and a 43 lens group G43 havingpositive refractive power. The 41 lens group G41 is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens L41 having a convex surface facing to the object cementedwith a positive meniscus lens L42 having a convex surface facing to theobject. The 42 lens group G42 is composed of, in order from the object,a positive meniscus lens L43 having a concave surface facing to theobject, and a double concave negative lens L44. The 43 lens group G43 iscomposed of, in order from the object, a double convex positive lensL45, and a positive meniscus lens L46 having convex surface facing tothe object.

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 42 lens group G42 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe first lens group G1 to the object.

In order to correct an image movement corresponding to a rotationalangle of θ by a lens system having the focal length of f, and vibrationreduction coefficient (the ratio of the moving amount of the image tothe moving amount of the vibration reduction lens group upon carryingout vibration reduction) of K, the vibration reduction lens group may bemoved by the amount of (f·tan θ)/K perpendicular to the optical axis.This relation is the same in the following examples and duplicatedexplanation is omitted.

In the wide-angle end state (W) of Example 5 of the second embodiment,vibration reduction coefficient K is 1.206, and the focal length f is71.50 (mm), so that the image rotation of 0.30° can be corrected bymoving the 42 lens group G42 by the amount of 0.311 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.800, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 42 lens group G42 by the amount of 0.428(mm).

Various values associated with Example 5 of the second embodiment of thepresent invention is listed in Table 5.

In [Moving Amount upon Focusing], 61 denotes a moving amount of thefirst lens group G1 to the object side focusing at the shooting distanceof 1500 (mm). TABLE 5 [Specifications] f = 71.50 134.90 294.00 FNO = 4.43  4.78  5.83 2ω = 34.69°  17.82°  8.25° [Lens Data] r d ν n 1106.9922 1.4000 30.13 1.698947 2 63.9533 8.5690 81.54 1.496999 3−244.9710 0.2000 4 126.9321 2.8438 53.20 1.693501 5 216.9031 (d5) 6−811.4085 3.2995 23.78 1.846660 7 −45.9839 1.0000 60.08 1.639999 853.9629 3.6848 9 −41.3222 1.0000 46.57 1.804000 10 403.6997 (d10) 11117.0360 3.4927 46.57 1.804000 12 −100.5857 1.5000 13 ∞ 1.0480 ApertureStop S 14 52.7514 5.2513 81.54 1.496999 15 −62.0004 1.0000 34.971.800999 16 −445.4607 0.2000 17 37.5205 2.9883 81.54 1.496999 18 74.7018(d18) 19 52.6572 1.4000 23.78 1.846660 20 16.3065 4.5499 45.78 1.54814121 76.4617 12.6826 22 −126.2398 3.9806 28.46 1.728250 23 −20.5284 0.200024 −20.6563 1.4000 46.57 1.804000 25 46.6744 4.6040 26 2036.2018 2.356129.23 1.721507 27 −113.7498 0.2000 28 47.0423 3.6545 34.97 1.800999 29343.9390 (B.f.) Wide-angle end Intermediate Telephoto end [VariableDistances] f 71.50000 134.90000 294.00000 d5 1.55195 36.01475 55.38418d10 34.15302 21.90257 1.00000 d18 18.78991 19.40071 22.11070 B.f.42.99999 49.92314 69.00000 [Moving Amount upon Focusing] f 71.500134.900 294.000 δ1 14.446 14.822 15.090 [Values for ConditionalExpressions] (10) f42/f4 = 0.356 (11) f4/fw = −1.483 (12) (1/f41 +1/f43) · f4 = −1.309 (13) n41N − n41P = 0.298 (14) ν42N −ν42P = 28.11(15) M2t = —

FIGS. 18A and 18B show various aberrations of the zoom lens systemaccording to Example 5 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 19 shows various aberrations of the zoom lenssystem according to Example 5 of the second embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 20A and20B show various aberrations of the zoom lens system according toExample 5 of the first embodiment in a telephoto end state upon focusingat infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 5 of the second embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 6

FIG. 21 is a diagram showing a sectional view of a zoom lens systemaccording to Example 6 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 21, a zoom lens system with a vibration reduction mechanismaccording to Example 6 is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, a third lens group G3 having positiverefractive power, and a fourth lens group G4 having negative refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1, thethird lens group G3, and the fourth lens group G4 move to the object andthe second lens group G2 moves once to an image I and, then, moves tothe object such that a distance between the first lens group G1 and thesecond lens group G2 increases, a distance between the second lens groupG2 and the third lens group G3 decreases, and a distance between thethird lens group G3 and the fourth lens group G4 varies.

The first lens group G1 is composed of, in order from the object, acemented lens constructed by a negative meniscus lens having a convexsurface facing to the object cemented with a double convex positivelens, and a positive meniscus lens having a convex surface facing to theobject.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconvex positive lens cemented with a double concave negative lens, and anegative meniscus lens having a concave surface facing to the object.

The third lens group G3 is composed of, in order from the object, adouble convex positive lens, a cemented lens constructed by a doubleconvex positive lens cemented with a double concave negative lens, and apositive meniscus lens having a convex surface facing to the object.

An aperture stop S is arranged to the object side of the third lensgroup G3 and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

The fourth lens group G4 is composed of, in order from the object, a 41lens group G41 having positive refractive power, a 42 lens group G42having negative refractive power, and a 43 lens group G43 havingpositive refractive power. The 41 lens group G41 is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens L41 having a convex surface facing to the object cementedwith a double convex positive lens L42. The 42 lens group G42 iscomposed of, in order from the object, a double convex positive lensL43, and a double concave negative lens L44. The 43 lens group G43 iscomposed of, in order from the object, a double convex positive lensL45, and a negative meniscus lens L46 having concave surface facing tothe object.

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 42 lens group G42 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe second lens group G2 to the object.

In the wide-angle end state (W) of Example 6 of the second embodiment,vibration reduction coefficient K is 1.054, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 42 lens group G42 by the amount of 0.355 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.800, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 42 lens group G42 by the amount of 0.428(mm).

Various values associated with Example 6 of the second embodiment of thepresent invention is listed in Table 6.

In [Moving Amount upon Focusing], 62 denotes a moving amount of thesecond lens group G2 to the object side focusing at the shootingdistance of 1500 (mm). TABLE 6 [Specifications] f = 71.40 134.90 294.00FNO =  4.03  4.61  5.83 2ω = 34.73°  17.96°  8.29° [Lens Data] r d ν n 1110.3430 1.8000 29.23 1.721507 2 69.3904 7.9665 81.54 1.496999 3−294.8326 0.2000 4 122.8189 2.6850 58.55 1.651597 5 181.6203 (d5) 6−3611.5709 1.4000 47.82 1.756998 7 49.7266 0.4871 8 57.7644 5.3831 23.781.846660 9 −42.0999 1.4000 36.26 1.620041 10 53.1079 4.0773 11 −38.08861.4000 34.97 1.800999 12 −502.7476 (d12) 13 ∞ 1.0000 Aperture Stop S 1497.5978 3.6622 58.55 1.651597 15 −81.8300 0.2000 16 48.0953 4.9666 81.541.496999 17 −62.0949 1.4000 34.97 1.800999 18 268.7785 0.2000 19 38.89023.2836 55.53 1.696797 20 54.2852 (d20) 21 78.0173 2.0000 23.78 1.84666022 24.6186 3.7355 64.14 1.516330 23 −185.3460 3.0000 24 176.2975 4.644227.79 1.740769 25 −25.6263 0.2072 26 −25.4689 1.4000 40.92 1.806098 2735.9916 3.3747 28 32.3977 4.1609 30.13 1.698947 29 −160.3892 4.5174 30−28.3572 1.4000 61.13 1.589130 31 −96.5409 (B.f.) Wide-angle endIntermediate Telephoto end [Variable Distances] f 71.40045 134.89998293.99991 d5 4.92513 37.53918 59.35524 d12 35.77592 21.59232 1.00000 d2024.34764 24.24866 24.69346 B.f. 40.00576 51.49527 75.00890 [MovingAmount upon Focusing] f 71.400 134.900 294.000 δ2 2.762 6.788 17.131[Values for Conditional Expressions] (10) f42/f4 = 0.366 (11) f4/fw =−1.891 (12) (1/f41 + 1/f43) · f4 = −1.866 (13) n41N − n41P = 0.330 (14)ν42N − ν42P = 13.13 (15) M2t = −0.950

FIGS. 22A and 22B show various aberrations of the zoom lens systemaccording to Example 6 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 23 shows various aberrations of the zoom lenssystem according to Example 6 of the second embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 24A and24B show various aberrations of the zoom lens system according toExample 6 of the second embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 6 of the second embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 7

FIG. 25 is a diagram showing a sectional view of a zoom lens systemaccording to Example 7 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 25, a zoom lens system with a vibration reduction mechanismaccording to Example 7 is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, a third lens group G3 having positiverefractive power, and a fourth lens group G4 having negative refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1, thethird lens group G3, and the fourth lens group G4 move to the object andthe second lens group G2 moves once to an image I and, then, moves tothe object such that a distance between the first lens group G1 and thesecond lens group G2 increases, a distance between the second lens groupG2 and the third lens group G3 decreases, and a distance between thethird lens group G3 and the fourth lens group G4 increases.

The first lens group G1 is composed of, in order from the object, acemented lens constructed by a negative meniscus lens having a convexsurface facing to the object cemented with a double convex positivelens, and a positive meniscus lens having a convex surface facing to theobject.

The second lens group G2 is composed of, in order from the object, anegative meniscus lens having a convex surface facing to the object, acemented lens constructed by a double concave negative lens cementedwith a double convex positive lens, and a negative meniscus lens havinga concave surface facing to the object.

The third lens group G3 is composed of, in order from the object, adouble convex positive lens, a cemented lens constructed by a doubleconvex positive lens cemented with a double concave negative lens, and apositive meniscus lens having a convex surface facing to the object.

An aperture stop S is arranged to the object side of the third lensgroup G3 and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

The fourth lens group G4 is composed of, in order from the object, a 41lens group G41 having negative refractive power, a 42 lens group G42having negative refractive power, and a 43 lens group G43 havingpositive refractive power. The 41 lens group G41 is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens L41 having a convex surface facing to the object cementedwith a double convex positive lens L42. The 42 lens group G42 iscomposed of, in order from the object, a double convex positive lensL43, and a double concave negative lens L44. The 43 lens group G43 iscomposed of, in order from the object, a double convex positive lensL45, and a negative meniscus lens L46 having concave surface facing tothe object.

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 42 lens group G42 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe second lens group G2 to the object.

In the wide-angle end state (W) of Example 7 of the second embodiment,vibration reduction coefficient K is 1.059, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 42 lens group G42 by the amount of 0.353 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.800, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 42 lens group G42 by the amount of 0.428(mm).

Various values associated with Example 7 of the second embodiment of thepresent invention is listed in Table 7.

In [Moving Amount upon Focusing], δ2 denotes a moving amount of thesecond lens group G2 to the object side focusing at the shootingdistance of 1500 (mm). TABLE 7 [Specifications] f = 71.40 134.90 294.00FNO =  3.99  4.52  5.75 2ω = 34.74°  17.97°  8.30° [Lens Data] r d ν n 192.3146 1.8000 34.97 1.800999 2 60.1527 9.0323 81.54 1.496999 3−249.0431 0.2000 4 80.8726 2.7760 70.23 1.487490 5 103.7057 (d5) 667.7254 1.4000 28.46 1.728250 7 34.1420 4.4733 8 −56.4538 1.4000 60.291.620411 9 40.9332 3.9004 23.78 1.846660 10 −339.3969 1.7837 11 −50.61221.4000 51.47 1.733997 12 −623.8156 (d12) 13 ∞ 1.0000 Aperture Stop S 14102.7196 3.8033 60.08 1.639999 15 −83.7403 0.2000 16 51.7820 5.204381.54 1.496999 17 −63.2478 1.4000 34.97 1.800999 18 327.7985 0.2000 1941.6150 3.5656 46.57 1.804000 20 67.4980 (d20) 21 65.4401 1.4000 23.781.846660 22 20.9137 3.9266 70.23 1.487490 23 −450.5603 4.1017 24167.1060 3.8379 28.46 1.728250 25 −25.2899 0.2000 26 −25.2945 1.400040.92 1.806098 27 36.0693 4.0874 28 32.4764 4.5076 30.13 1.698947 29−134.5935 4.2066 30 −31.0368 1.4000 60.08 1.639999 31 −108.8255 (B.f.)Wide-angle end Intermediate Telephoto end [Variable Distances] f71.40000 134.90000 294.00000 d5 4.03725 36.57205 57.18679 d12 34.4640820.96534 1.00000 d20 23.89184 23.91724 24.20639 B.f. 40.00000 50.6546074.99996 [Moving Amount upon Focusing] f 71.400 134.900 294.000 δ2 2.5396.520 16.557 [Values for Conditional Expressions] (10) f42/f4 = 0.505(11) f4/fw = −1.358 (12) (1/f41 + 1/f43) · f4 = −1.079 (13) n41N = n41P= 0.359 (14) ν42N − ν42P = 12.46 (15) M2t = −0.961

FIGS. 26A and 26B show various aberrations of the zoom lens systemaccording to Example 7 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 27 shows various aberrations of the zoom lenssystem according to Example 7 of the second embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 28A and28B show various aberrations of the zoom lens system according toExample 7 of the second embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.150,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 7 of the second embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 8

FIG. 29 is a diagram showing a sectional view of a zoom lens systemaccording to Example 8 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 29, a zoom lens system with a vibration reduction mechanismaccording to Example 8 is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, a third lens group G3 having positiverefractive power, and a fourth lens group G4 having negative refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1, thethird lens group G3, and the fourth lens group G4 move to the object andthe second lens group G2 moves once to an image I and, then, moves tothe object such that a distance between the first lens group G1 and thesecond lens group G2 increases, a distance between the second lens groupG2 and the third lens group G3 decreases, and a distance between thethird lens group G3 and the fourth lens group G4 varies.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a double convex positive lens, and adouble concave negative lens.

The third lens group G3 is composed of, in order from the object, adouble convex positive lens, a cemented lens constructed by a doubleconvex positive lens cemented with a double concave negative lens, and apositive meniscus lens having a convex surface facing to the object.

An aperture stop S is arranged to the object side of the third lensgroup G3 and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

The fourth lens group G4 is composed of, in order from the object, a 41lens group G41 having positive refractive power, a 42 lens group G42having negative refractive power, and a 43 lens group G43 havingpositive refractive power. The 41 lens group G41 is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens L41 having a convex surface facing to the object cementedwith a double convex positive lens L42. The 42 lens group G42 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens L43 cemented with a double concave negativelens L44. The 43 lens group G43 is composed of, in order from theobject, a double convex positive lens L45, and a negative meniscus lensL46 having concave surface facing to the object.

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 42 lens group G42 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 8 of the second embodiment,vibration reduction coefficient K is 1.395, and the focal length f is71.40 (mm), so that the image rotation of 0.300 can be corrected bymoving the 42 lens group G42 by the amount of 0.268 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 2.261, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 42 lens group G42 by the amount of 0.340(mm).

Various values associated with Example 8 of the second embodiment of thepresent invention is listed in Table 8.

In [Moving Amount upon Focusing], δ1B denotes a moving amount of the 1Blens group G1B to the object side focusing at the shooting distance of1500 (mm). TABLE 8 [Specifications] f = 71.40 135.20 294.00 FNO =  3.98 4.42  5.83 2ω = 34.26°  17.57°  8.19° [Lens Data ] r d ν n 1 401.12923.4320 64.14 1.516330 2 −401.1292 (d2) 3 73.7120 1.8000 28.46 1.728250 449.4588 9.2239 81.54 1.496999 5 −634.7712 (d5) 6 −569.6277 1.4000 46.571.804000 7 65.8130 2.9470 8 −66.3802 1.4000 49.34 1.743198 9 37.45354.4348 23.78 1.846660 10 −157.1502 1.2424 11 −56.4033 1.4000 46.571.804000 12 457.6562 (d12) 13 ∞ 1.0000 Aperture Stop S 14 174.88834.0762 60.08 1.639999 15 −54.3627 0.2000 1.000000 16 52.6528 6.076681.54 1.496999 17 −40.7675 1.4000 34.97 1.800999 18 1440.7843 0.2000 1933.5705 3.5534 61.13 1.589130 20 93.9894 (d20) 21 479.6438 1.4000 23.781.846660 22 43.7293 4.5629 59.84 1.522494 23 −51.1261 3.0000 241129.8061 3.6174 29.23 1.721507 25 −22.8122 1.4000 47.93 1.717004 2629.6916 4.4859 27 35.9110 3.4607 33.79 1.647689 28 −167.9338 4.3753 29−22.4279 1.4000 46.57 1.804000 30 −45.1019 (B.f.) Wide-angle endIntermediate Telephoto end [Variable Distances] f 71.39999 135.19963294.00017 d2 13.96876 13.96876 13.96876 d5 1.50000 30.16863 45.04078 d1226.95417 16.63929 1.00000 d20 15.26706 15.23225 16.01169 B.f. 45.8216354.27048 80.82164 [Moving Amount upon Focusing] f 71.400 135.200 294.000δ1B 12.512 12.783 13.064 [Values for Conditional Expressions] (10)f42/f4 = 0.579 (11) f4/fw = −1.039 (12) (1/f41 + 1/f43) · f4 = −0.816(13) n41N − n41P = 0.324 (14) ν42N − ν42P = 18.70 (15) M2t = —

FIGS. 30A and 30B show various aberrations of the zoom lens systemaccording to Example 8 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 31 shows various aberrations of the zoom lenssystem according to Example 8 of the second embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 32A and32B show various aberrations of the zoom lens system according toExample 8 of the second embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 8 of the second embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 9

FIG. 33 is a diagram showing a sectional view of a zoom lens systemaccording to Example 9 of the second embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 33, a zoom lens system with a vibration reduction mechanismaccording to Example 9 is composed of, in order from an object, a firstlens group G1 having positive refractive power, a second lens group G2having negative refractive power, a third lens group G3 having positiverefractive power, a fourth lens group G4 having negative refractivepower, and a fifth lens group G5 having positive refractive power. Whenthe state of lens group positions varies from a wide-angle end state (W)to a telephoto end state (T), the first lens group G1, the third lensgroup G3, the fourth lens group G4, and the fifth lens group G5 move tothe object and the second lens group G2 moves once to the object and,then, moves to an image I such that a distance between the first lensgroup G1 and the second lens group G2 increases, a distance between thesecond lens group G2 and the third lens group G3 decreases, a distancebetween the third lens group G3 and the fourth lens group G4 increases,and a distance between the fourth lens group G4 and the fifth lens groupdecreases.

The first lens group G1 is composed of, in order from the object, acemented lens constructed by a negative meniscus lens having a convexsurface facing to the object cemented with a double convex positivelens, and a positive meniscus lens having a convex surface facing to theobject.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, and a cemented lens constructed by adouble concave negative lens cemented with a double convex positivelens.

The third lens group G3 is composed of, in order from the object, aplano-convex positive lens having a convex surface facing to the image,a double convex positive lens, a negative meniscus lens having a concavesurface facing to the object, and a double convex positive lens.

An aperture stop S is arranged to the object side of the third lensgroup G3 and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

The fourth lens group G4 is composed of, in order from the object, a 41lens group G41 having positive refractive power, a 42 lens group G42having negative refractive power, and a 43 lens group G43 havingnegative refractive power. The 41 lens group G41 is composed of a doubleconvex positive lens L41. The 42 lens group G42 is composed of, in orderfrom the object, a double concave negative lens L42, and a positivemeniscus lens L43 having a convex surface facing to the object. The 43lens group G43 is composed of a negative meniscus lens L44 having aconcave surface facing to the object.

The fifth lens group G5 is composed of, in order from the object, anegative meniscus lens having a convex surface facing to the object, adouble convex positive lens, and a negative meniscus lens having aconcave surface facing to the object.

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 42 lens group G42 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe second lens group G2 to the object.

In the wide-angle end state (W) of Example 9 of the second embodiment,vibration reduction coefficient K is 1.719, and the focal length f is69.99 (mm), so that the image rotation of 0.30° can be corrected bymoving the 42 lens group G42 by the amount of 0.213 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 2.284, andthe focal length f is 299.93 (mm), so that the image rotation of 0.15°can be corrected by moving the 42 lens group G42 by the amount of 0.344(mm).

Various values associated with Example 9 of the second embodiment of thepresent invention is listed in Table 9.

In [Moving Amount upon Focusing], δ2 denotes a moving amount of thesecond lens group G2 to the object side focusing at the shootingdistance of 1500 (mm). TABLE 9 [Specifications] f = 69.99 134.96 299.93FNO =  4.31  5.28  5.77 2ω = 34.39°  17.94°  8.06° [Lens Data] r d ν n 1105.7828 1.5000 25.43 1.805180 2 74.2801 7.7806 81.61 1.497000 3−314.2885 0.5000 4 84.1721 4.0034 81.61 1.497000 5 192.0413 (d5) 6−289.0462 1.5000 49.61 1.772500 7 37.2942 5.1639 8 −36.2718 1.5000 53.851.713000 9 42.3070 3.9288 23.78 1.846660 10 −275.6800 (d10) 11 ∞ 0.5000Aperture Stop S 12 ∞ 2.5521 49.61 1.772500 13 −91.7378 0.5000 14 44.26116.7347 81.61 1.497000 15 −34.2879 0.6605 16 −32.1236 1.5000 37.171.834000 17 −239.8905 0.5000 18 48.9662 4.7058 81.61 1.497000 19−95.8226 (d19) 20 38.7220 5.1115 81.61 1.497000 21 −81.1156 3.8000 22−1244.0407 1.5000 46.63 1.816000 23 18.1395 0.5544 24 18.4154 3.990234.47 1.639800 25 57.0111 3.8499 26 −24.5068 1.5000 49.32 1.743200 27−42.2340 (d27) 28 106.2163 1.5000 23.78 1.846660 29 36.1752 3.2036 3051.9898 4.5496 33.04 1.666800 31 −45.3816 3.9985 32 −24.1064 1.500046.63 1.816000 33 −36.1573 (B.f.) Wide-angle end Intermediate Telephotoend [Variable Distances] f 69.98593 134.95979 299.92772 d5 7.7709731.32565 57.66235 d10 25.75941 15.14446 0.50000 d19 3.94280 7.031577.76808 d27 10.15139 2.54225 0.50000 B.f. 50.26987 74.11967 85.25814[Moving Amount upon Focusing] f 69.986 134.960 299.928 δ2 1.324 2.86512.223 [Values for Conditional Expressions] (10) f42/f4 = 0.484 (11)f4/fw = −1.353 (12) (1/f41 + 1/f43) · f4 = −0.608 (13) n41N − n41P = —(14) ν42N − ν42P = — (15) M2t = −0.973

FIGS. 34A and 34B show various aberrations of the zoom lens systemaccording to Example 9 of the second embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 35 shows various aberrations of the zoom lenssystem according to Example 9 of the second embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 36A and36B show various aberrations of the zoom lens system according toExample 9 of the second embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 9 of the second embodiment shows superb optical performancecorrecting various aberrations.

Third Embodiment

A zoom lens system according to a third embodiment of the presentinvention is explained below.

The zoom lens system with a vibration reduction mechanism according tothe third embodiment of the present invention is composed of, in orderfrom an object, a first lens group having positive refractive power, asecond lens group having negative refractive power, and a third lensgroup having positive refractive power. When the state of lens grouppositions varies from a wide-angle end state to a telephoto end state, adistance between the first lens group and the second lens groupincreases, and a distance between the second lens group and the thirdlens group decreases. The construction is effective for simplifying theconstruction and shortening the total lens length.

The third lens group G3 is composed of, in order from the object, a 31lens group having positive refractive power, a 32 lens group havingnegative refractive power, and a 33 lens group having positiverefractive power. Upon detecting a camera shake, vibration reduction iscarried out by moving only the 32 lens group perpendicular to theoptical axis. By arranging positive refractive power to the 31 lensgroup and negative refractive power to the 32 lens group, the effectivediameter of the 32 lens group can be small relative to those of thefirst lens group through the 31 lens group. Accordingly, the vibrationreduction mechanism can be compact, so that it is effective for the zoomlens system as a whole to be compact. By constructing in this manner,degradation of optical performance caused by moving the 32 lens groupperpendicular to the optical axis can be reduced.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expressions (16) through (20) are preferably satisfied:1.40<f1/fw<2.00  (16)−0.53<f2/fw<−0.32  (17)0.35<f3/fw<0.65  (18)−2.00<f32/f3<−0.80  (19)−0.20<f3/f33<0.50  (20)where fw denotes the focal length of the zoom lens system in thewide-angle end state, f1 denotes the focal length of the first lensgroup, f2 denotes the focal length of the second lens group, f3 denotesthe focal length of the third lens group, f32 denotes the focal lengthof the 32 lens group, and f33 denotes the focal length of the 33 lensgroup.

Conditional expression (16) defines an appropriate range of the focallength of the first lens group. When the ratio f1/fw is equal to orexceeds the upper limit of conditional expression (16), refractive powerof the first lens group becomes weak, so that the total lens length ofthe zoom lens system becomes large. On the other hand, when the ratiof1/fw is equal to or falls below the lower limit of conditionalexpression (16), refractive power of the first lens group becomes large,so that it becomes difficult to correct spherical aberration and on-axischromatic aberration. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (16) to 1.50 and the upper limit to 1.90.

Conditional expression (17) defines an appropriate range of the focallength of the second lens group. When the ratio f2/fw is equal to orexceeds the upper limit of conditional expression (17), negativerefractive power of the second lens group becomes large, so that itbecomes difficult to correct spherical aberration and coma. On the otherhand, when the ratio f2/fw is equal to or falls below the lower limit ofconditional expression (17), negative refractive power of the secondlens group becomes weak, so that it becomes difficult to obtain the zoomratio of about four. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (17) to −0.50 and the upper limit to −0.35.

Conditional expression (18) defines an appropriate range of the focallength of the third lens group. When the ratio f3/fw is equal to orexceeds the upper limit of conditional expression (18), refractive powerof the third lens group becomes weak, so that the total lens length ofthe zoom lens system becomes large. On the other hand, when the ratiof3/fw is equal to or falls below the lower limit of conditionalexpression (18), refractive power of the third lens group becomes large,so that it becomes difficult to correct various aberrations as well asspherical aberration. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (18) to 0.40 and the upper limit to 0.60.

Conditional expression (19) defines an appropriate range of the focallength of the 32 lens group. When the ratio f32/f3 is equal to orexceeds the upper limit of conditional expression (19), negativerefractive power of the 32 lens group becomes large, so that the ratioof the moving amount of image relative to the moving amount of the 32lens group upon vibration reduction becomes large. Accordingly,permissible driving error of the 32 lens group upon vibration reductionbecomes small, so that it becomes difficult to control the 32 lensgroup. On the other hand, when the ratio f32/f3 is equal to or fallsbelow the lower limit of conditional expression (19), negativerefractive power of the 32 lens group becomes small, so that the ratioof the moving amount of image relative to the moving amount of the 32lens group upon vibration reduction becomes small. Accordingly, movingamount of the 32 lens group upon vibration reduction becomes large, sothat the vibration reduction mechanism becomes large. In order tofurther secure the effect of the present invention, it is desirable toset the lower limit of conditional expression (19) to −1.85 and theupper limit to −0.90.

Conditional expression (20) defines an appropriate range of the focallength of the 33 lens group. When the ratio f3/f33 is equal to orexceeds the upper limit of conditional expression (20), positiverefractive power of the 33 lens group becomes large, so that the totallens length of the zoom lens system becomes large. On the other hand,when the ratio f3/f33 is equal to or falls below the lower limit ofconditional expression (20), negative refractive power of the 33 lensgroup becomes large, so that it becomes difficult to correct coma anddistortion. In order to further secure the effect of the presentinvention, it is desirable to set the lower limit of conditionalexpression (20) to −0.15 and the upper limit to 0.40.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe first lens group and the third lens group move to the object whenthe state of lens group positions varies from the wide-angle end stateto the telephoto end state. By construction like this, the total lenslength of the zoom lens system in the wide-angle end state can be short,so that the zoom lens system can be compact.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe 31 lens group includes at least three positive lens elements and atleast one negative lens element, the 32 lens group includes at least onepositive lens element and at least one negative lens element, and the 33lens group includes at least one positive lens element and at least onenegative lens element. By constructing like this, decentering aberrationcaused upon vibration reduction can be satisfactorily corrected.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe 31 lens group is composed of, in order from the object, a doubleconvex positive lens, a first cemented lens constructed by a doubleconvex positive lens cemented with a negative lens having a concavesurface facing to the object, a positive meniscus lens having a convexsurface facing to the object, and a second cemented lens. With thisconstruction, decentering aberration caused upon vibration reduction canbe satisfactorily corrected.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expressions (21) and (22) are preferably satisfied:0.20<n31N−n31P  (21)30.0<ν31P−ν31N  (22)where n31N denotes refractive index of the negative lens in the firstcemented lens at d-line (λ=587.6 nm), n31P denotes refractive index ofthe double convex positive lens in the first cemented lens at d-line,ν31N denotes Abbe number of the negative lens in the first cemented lensat d-line, and ν31P denotes Abbe number of the double convex positivelens in the first cemented lens at d-line.

Conditional expression (21) defines an appropriate range of thedifference in refractive indices between the double convex positive lensand the negative lens in the first cemented lens. When the differencen31N−n31P is equal to or falls below the lower limit of conditionalexpression (21), it becomes difficult to satisfactorily correctspherical aberration. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (21) to 0.25.

Conditional expression (22) defines an appropriate range of thedifference in Abbe numbers between the double convex positive lens andthe negative lens in the first cemented lens. When the differenceν31P−ν31N I equal to or falls below the lower limit of conditionalexpression (22), it becomes difficult to satisfactorily correct lateralchromatic aberration. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (22) to 35.0.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe 32 lens group is composed of, in order from the object, a positivelens having a convex surface facing to the object, and a double concavenegative lens. With this construction, decentering aberration causedupon vibration reduction can be satisfactorily corrected.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expression (23) is preferably satisfied:10.0<ν32N−ν32P  (23)where ν32N denotes Abbe number of the double concave negative lens inthe 32 lens group at d-line (λ=587.6 nm), and ν32P denotes Abbe numberof the positive lens in the 32 lens group at d-line.

Conditional expression (23) defines an appropriate range of thedifference in Abbe numbers between the double concave negative lens andthe positive lens in the 32 lens group. When the difference ν32N−ν32P isequal to or falls below the lower limit of conditional expression (23),it becomes difficult to correct lateral chromatic aberration caused bydecentering upon vibration reduction. In order to further secure theeffect of the present invention, it is desirable to set the lower limitof conditional expression (23) to 12.0.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe 32 lens group is composed of, in order from the object, a cementedlens constructed by a positive lens having a convex surface facing tothe image cemented with a double concave negative lens. With thisconstruction, decentering aberration caused upon vibration reduction canbe satisfactorily corrected.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expression (24) is preferably satisfied:−2.00<(r32R+r32F)/(r32R−r32F)<−0.70  (24)where r32F denotes the radius of curvature of the object side surface ofthe positive lens in the 32 lens group, r32R denotes the radius ofcurvature of the image side surface of the double concave negative lensin the 32 lens group.

Conditional expression (24) defines an appropriate range of the shape ofthe cemented lens in the 32 lens group. When the value(r32R+r32F)/(r32R−r32F) exceeds the upper limit of conditionalexpression (24) or falls below the lower limit of conditional expression(24), production of decentering aberration caused upon vibrationreduction becomes large. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (24) to −1.90 and the upper limit to −0.80.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expression (25) is preferably satisfied:0.40<r32S/f32<0.90  (25)where r32S denotes the radius of curvature of the cemented surface ofthe cemented lens in the 32 lens group, and f32 denotes the focal lengthof the 32 lens group.

Conditional expression (25) defines an appropriate range of the radiusof curvature of the cemented surface of the cemented lens in the 32 lensgroup. When the ratio r32S/f32 exceeds the upper limit of conditionalexpression (25) or falls below the lower limit of conditional expression(25), production of decentering aberration caused upon vibrationreduction becomes large. In order to further secure the effect of thepresent invention, it is desirable to set the lower limit of conditionalexpression (25) to 0.45 and the upper limit to 0.85.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, it is preferable thatthe zoom lens system consists only of a first lens group, a second lensgroup, and a third lens group. By arranging no lens group withrefractive power to the image side of the third lens group, the zoomlens system can be simple.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the first lens groupis composed of, in order from the object, it is preferable that a 1Alens group having positive refractive power and a 1B lens group havingpositive refractive power, and focusing from infinity to a close-rangeobject is carried out by moving only the 1B lens group to the object.

In the zoom lens system with a vibration reduction mechanism accordingto the third embodiment of the present invention, the followingconditional expression (26) is preferably satisfied:1.70<f1A/f1B<4.00  (26)where f1A denotes the focal length of the 1A lens group, and f1B denotesthe focal length of the 1B lens group.

Conditional expression (26) defines an appropriate range of the ratio ofthe focal length of the 1A lens group to that of the 1B lens group. Whenthe ratio f1A/f1B is equal to or exceeds the upper limit of conditionalexpression (26), refractive power of the 1B lens group becomes small, sothat variation in various aberrations upon focusing becomes large. Onthe other hand, when the ratio f1A/f1B is equal to or falls below thelower limit of conditional expression (26), refractive power of the 1Alens group becomes small, so that moving amount of the 1A lens groupupon focusing becomes large. Accordingly, the zoom lens system becomeslarge. In order to further secure the effect of the present invention,it is desirable to set the lower limit of conditional expression (26) to1.90 and the upper limit to 3.50.

Each example according to the third embodiment of the present inventionis explained below with reference to accompanying drawings.

EXAMPLE 10

FIG. 37 is a diagram showing a sectional view of a zoom lens systemaccording to Example 10 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 37, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingpositive refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with a doubleconcave negative lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged between the positive meniscus lens andthe second cemented lens in the 31 lens group G31, and is moved togetherwith the third lens group G3 upon zooming from the wide-angle end state(W) to the telephoto end state (T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 10 of the third embodiment,vibration reduction coefficient K is 1.47, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.254 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 2.68, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.287(mm).

Various values associated with Example 10 of the third embodiment of thepresent invention is listed in Table 10.

In [Moving Amount upon Focusing], δ1B denotes a moving amount of the 1Blens group G1B to the object side focusing at the shooting distance of1500 (mm). TABLE 10 [Specifications] f = 71.40 134.90 294.00 FNO =  4.10 4.28  5.79 2ω = 22.50°  11.75°  5.44° [Lens Data ] r d ν n 1 485.25173.3856 64.14 1.516330 2 −485.2517 (d2) 3 74.6948 2.5000 26.52 1.761821 450.2473 8.5338 70.23 1.487490 5 −397.6433 (d5) 6 −445.5319 1.4000 49.601.772499 7 121.5057 1.7612 8 −139.8007 1.4000 49.60 1.772499 9 31.40334.4544 23.78 1.846660 10 195.1690 2.3037 11 −63.0020 1.4000 49.601.772499 12 863.7974 (d12) 13 209.2396 3.4957 51.47 1.733997 14 −78.55390.2000 15 53.3010 6.1013 81.54 1.496999 16 −47.6905 1.4000 34.971.800999 17 743.9564 0.2000 18 31.2964 4.0974 60.64 1.603112 19 86.895112.4001 20 ∞ 1.0000 Aperture Stop S 21 67.3937 1.3000 23.78 1.846660 2226.7354 5.4922 70.23 1.487490 23 −88.9999 5.5185 24 1974.4906 3.705226.52 1.761821 25 −26.6771 1.2000 49.60 1.772499 26 26.6771 3.2607 2729.4872 3.9533 34.47 1.639799 28 −93.8522 2.2384 29 −21.9460 1.200049.60 1.772499 30 −59.2566 (B.f.) Wide-angle end Intermediate Telephotoend [Variable Distances] (Infinity) f 71.40000 134.90024 294.00000 d216.01875 16.01875 16.01875 d5 2.00000 31.41839 42.84564 d12 32.4549519.43707 2.00000 B.f. 40.62478 47.41150 80.62502 [Moving Amount uponFocusing] f 71.40000 134.90024 294.00000 δ1B 13.70747 13.96627 14.28274[Values for Conditional Expressions] (16) f1/f2 = 1.773 (17) f2/fw =−0.463 (18) f3/fw = 0.500 (19) f32/f3 = −0.9678 (20) f3/f33 = 0.306 (21)n31N − n31P = 0.304 (22) ν31P − ν31N = 46.57 (23) ν32N −ν32P = 23.08(24) (r32R + r32F)/(r32R −r32F) = −1.027 (25) r32S/f32 = 0.772 (26)f1A/f1B = 2.819

FIGS. 38A and 38B show various aberrations of the zoom lens systemaccording to Example 10 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 39 shows various aberrations of the zoom lenssystem according to Example 10 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 40A and40B show various aberrations of the zoom lens system according toExample 10 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.150,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 10 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 11

FIG. 41 is a diagram showing a sectional view of a zoom lens systemaccording to Example 11 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 41, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingpositive refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with a doubleconcave negative lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged between the positive meniscus lens andthe second cemented lens in the 31 lens group G31, and is moved togetherwith the third lens group G3 upon zooming from the wide-angle end state(W) to the telephoto end state (T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 11 of the third embodiment,vibration reduction coefficient K is 1.02, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.367 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.70, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.453(mm).

Various values associated with Example 11 of the third embodiment of thepresent invention is listed in Table 11. TABLE 11 [Specifications] f =71.40 134.90 294.00 FNO =  4.10  4.28  5.79 2ω = 22.51°  11.74°  5.43°[Lens Data] r d ν n 1 494.1160 3.3593 64.14 1.516330 2 −494.1160 (d2) 374.6142 2.5000 26.52 1.761821 4 50.2492 8.5170 70.23 1.487490 5−409.6962 (d5) 6 −572.2854 1.4000 49.60 1.772499 7 118.2999 1.5934 8−150.1597 1.4000 49.60 1.772499 9 28.9590 4.2332 23.78 1.846660 10159.4762 2.3641 11 −56.2166 1.4000 49.60 1.772499 12 737.8222 (d12) 13255.4424 3.4925 51.47 1.733997 14 −65.2491 0.2000 15 55.4617 5.867781.54 1.496999 16 −42.2335 1.4000 34.97 1.800999 17 391.1593 0.2000 1829.8308 4.2307 60.64 1.603112 19 109.3078 9.9568 20 ∞ 1.0000 ApertureStop S 21 111.2314 1.3000 23.78 1.846660 22 34.2913 3.8688 70.231.487490 23 −116.1639 3.0066 24 131.0022 2.6204 25.42 1.805181 25−42.8081 1.2000 39.58 1.804398 26 35.6448 6.4837 27 44.2831 3.9886 31.071.688931 28 −53.8284 2.7522 29 −23.7792 1.2000 49.60 1.772499 30−254.9277 (B.f.) Wide-angle end Intermediate Telephoto end [VariableDistances] (Infinity) f 71.40000 134.90024 294.00000 d2 16.2214116.22141 16.22141 d5 2.00000 33.62022 46.49954 d12 29.66797 18.379912.00000 B.f. 47.57563 53.66382 85.74428 [Moving Amount upon Focusing] f71.40000 134.90024 294.00000 δ1B 13.90148 14.20164 13.03481 [Values forConditional Expressions] (16) f1/fw = 1.787 (17) f2/f2 = −0.436 (18)f3/fw = 0.500 (19) f32/f3 = −1.738 (20) f3/f33 = 0.063 (21) n31N − n31P= 0.304 (22) ν31P − ν31N = 46.57 (23) ν32N − ν32P = 14.16 (24) (r32R +r32F)/(r32R − r32F) = −1.748 (25) r32S/f32 = 0.690 (26) f1A/f1B = 2.860

FIGS. 42A and 42B show various aberrations of the zoom lens systemaccording to Example 11 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 43 shows various aberrations of the zoom lenssystem according to Example 11 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 44A and44B show various aberrations of the zoom lens system according toExample 11 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 11 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 12

FIG. 45 is a diagram showing a sectional view of a zoom lens systemaccording to Example 12 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 45, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingnegative refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with a doubleconcave negative lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged to the object side of the 31 lens groupG31, and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 12 of the third embodiment,vibration reduction coefficient K is 1.20, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.312 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.80, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.428(mm).

Various values associated with Example 12 of the third embodiment of thepresent invention is listed in Table 12. TABLE 12 [Specifications] f =71.40 134.90 294.00 FNO =  4.11  4.34  5.80 2ω = 22.59°  11.77°  5.43°[Lens Data] r d ν n 1 470.2040 3.4304 64.14 1.516330 2 −470.2040 (d2) 366.8958 2.5000 26.52 1.761821 4 45.5528 9.0276 70.23 1.487490 5−449.7939 (d5) 6 −402.2639 1.4000 49.60 1.772499 7 87.3056 1.8292 8−109.2528 1.4000 49.60 1.772499 9 27.2177 4.2493 23.78 1.846660 10238.8473 2.0018 11 −54.2941 1.4000 49.60 1.772499 12 405.9871 (d12) 13 ∞1.0000 Aperture Stop S 14 202.2803 3.3407 51.47 1.733997 15 −69.75140.2000 16 49.4756 6.2066 81.54 1.496999 17 −36.3641 1.4000 34.971.800999 18 417.1479 0.2000 19 30.2273 4.0221 60.64 1.603112 20 106.70844.7396 21 66.4249 1.3000 23.78 1.846660 22 38.1999 4.3369 70.23 1.48749023 −91.4989 3.0000 24 195.2029 2.8722 25.42 1.805181 25 −40.8879 1.200039.58 1.804398 26 39.1832 12.6471 27 71.7192 2.3982 31.07 1.688931 28−76.4137 1.3004 29 −21.7636 1.2000 49.60 1.772499 30 −61.3686 (B.f.)Wide-angle end Intermediate Telephoto end [Variable Distance] (Infinity)f 71.40008 134.89998 294.00000 d2 14.05307 14.05307 14.05307 d5 2.0000033.03379 46.59044 d12 25.89044 16.74440 2.00000 B.f. 54.45490 59.3458888.75509 [Moving Amount upon Focusing] f 71.40008 134.89998 294.00000δ1B 11.82193 12.07969 12.36388 [Values for Conditional Expressions] (16)f1/f2 = 1.653 (17) f2/fw = −0.379 (18) f3/fw = 0.491 (19) f32/f3 =−1.762 (20) f3/f33 = −0.120 (21) n31N − n31P = 0.304 (22) ν31P − ν31N =46.57 (23) ν32N − ν32P = 13.93 (24) (r32R + r32F)/(r32R − r32F) = −1.502(25) r32S/f32 = 0.662 (26) f1A/f1B = 2.960

FIGS. 46A and 46B show various aberrations of the zoom lens systemaccording to Example 12 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 47 shows various aberrations of the zoom lenssystem according to Example 12 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 48A and48B show various aberrations of the zoom lens system according toExample 12 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 12 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 13

FIG. 49 is a diagram showing a sectional view of a zoom lens systemaccording to Example 13 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 49, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingnegative refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with a doubleconcave negative lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged between the 32 lens group G32 and the 33lens group G33, and is moved together with the third lens group G3 uponzooming from the wide-angle end state (W) to the telephoto end state(T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 13 of the third embodiment,vibration reduction coefficient K is 1.22, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.306 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.77, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.435(mm).

Various values associated with Example 13 of the third embodiment of thepresent invention is listed in Table 13. TABLE 13 [Specifications] f =71.40 134.90 294.00 FNO =  3.99  4.07  5.80 2ω = 22.60°  11.74°  5.43°[Lens Data] r d ν n 1 435.2356 3.5738 64.14 1.516330 2 −435.2356 (d2) 365.0718 2.5000 26.52 1.761821 4 44.2697 9.2741 70.23 1.487490 5−463.1280 (d5) 6 −312.4330 1.4000 49.60 1.772499 7 89.0862 1.9706 8−89.6775 1.4000 49.60 1.772499 9 27.3391 4.2567 23.78 1.846660 10234.4984 1.8028 11 −63.7183 1.4000 49.60 1.772499 12 421.2241 (d12) 13128.9757 3.6394 49.34 1.743198 14 −65.2871 0.2000 15 45.1211 6.214181.54 1.496999 16 −34.9173 1.4000 33.89 1.803840 17 179.4381 0.2000 1828.1967 3.1441 61.13 1.589130 19 51.4191 3.2906 20 61.2265 1.3000 23.781.846660 21 41.2033 4.3881 70.23 1.487490 22 −71.4444 3.0000 232400.8873 2.8952 25.42 1.805181 24 −34.5253 1.2000 40.10 1.762001 2543.6975 3.0000 26 ∞ 10.7331 Aperture Stop S 27 109.9589 2.6855 33.791.647689 28 −56.7968 1.6430 29 −21.1003 1.2000 50.23 1.719995 30−54.1165 (B.f.) Wide-angle end Intermediate Telephoto end 8 VariableDistances] (Infinity) f 71.40000 134.90000 294.00000 d2 13.5136313.51363 13.51363 d5 2.06047 33.56902 45.03690 d12 27.97643 18.337992.00000 B.f. 55.73858 57.28561 87.73867 [Moving Amount upon Focusing] f71.40000 134.90000 294.00000 δ1B 11.13016 11.34131 11.58141 [Values forConditional Expressions] (16) f1/fw = 1.600 (17) f2/fw = −0.382 (18)f3/fw = 0.512 (19) f32/f3 = −1.730 (20) f3/f33 = −0.099 (21) n31N − n31P= 0.307 (22) ν31P − ν31N = 47.65 (23) ν32N − ν32P = 14.68 (24) (r32R +r32F)/(r32R − r32F) = −1.037 (25) r32S/f32 = 0.546 (26) f1A/f1B = 2.791

FIGS. 50A and 50B show various aberrations of the zoom lens systemaccording to Example 13 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 51 shows various aberrations of the zoom lenssystem according to Example 13 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 52A and52B show various aberrations of the zoom lens system according toExample 13 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 13 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 14

FIG. 53 is a diagram showing a sectional view of a zoom lens systemaccording to Example 14 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 53, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingnegative refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with anegative meniscus lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged between the 31 lens group G31 and the 32lens group G32, and is moved together with the third lens group G3 uponzooming from the wide-angle end state (W) to the telephoto end state(T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 14 of the third embodiment,vibration reduction coefficient K is 1.20, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.312 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.75, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.440(mm).

Various values associated with Example 14 of the third embodiment of thepresent invention is listed in Table 14. TABLE 14 [Specifications] f =71.40 134.91 294.00 FNO =  4.07  4.21  5.80 2ω = 22.52°  11.72°  5.42°[Lens Data] r d ν n 1 469.3093 3.4317 64.14 1.516330 2 −469.3093 (d2) 370.6717 2.5000 26.52 1.761821 4 47.9817 8.6474 70.23 1.487490 5−513.7728 (d5) 6 −449.1622 1.4000 49.60 1.772499 7 121.4673 1.3256 8−170.8246 1.4000 49.60 1.772499 9 25.7253 4.1467 23.78 1.846660 10114.2679 2.1893 11 −58.0505 1.4000 49.60 1.772499 12 427.6062 (d12) 13184.6338 3.0978 52.64 1.740999 14 −77.4294 0.2000 15 60.5320 6.288681.54 1.496999 16 −38.0057 1.4000 34.97 1.800999 17 −2769.6388 0.2000 1829.4015 3.3326 60.64 1.603112 19 65.7395 7.2941 20 48.4532 1.3000 23.781.846660 21 28.7258 4.3311 70.23 1.487490 22 −116.3213 1.4000 23 ∞3.6000 Aperture Stop S 24 192.1240 2.6534 25.42 1.805181 25 −39.86091.2000 39.58 1.804398 26 36.5000 8.1971 27 74.0134 3.9109 31.07 1.68893128 −49.3643 1.8413 29 −22.3167 1.2000 49.60 1.772499 30 −89.5841 (B.f.)Wide-angle end Intermediate Telephoto end [Variable Distances](Infinity) f 71.40015 134.90898 294.00094 d2 15.55650 15.55650 15.55650d5 2.00494 36.17786 49.70524 d12 29.70030 19.40726 2.00000 B.f. 51.8508754.13440 80.85104 [Moving Amount upon Focusing] f 71.40015 134.90898294.00094 δ1B 13.28566 13.56940 13.82723 [Values for ConditionalExpressions] (16) f1/fw = 1.743 (17) f2/fw = −0.414 (18) f3/fw = 0.506(19) f32/f3 = −1.569 (20) f3/f33 = −0.048 (21) n31N − n31P = 0.304 (22)ν31P − ν32P = 46.57 (23) ν32N − ν32P = 14.16 (24) (r32R + r32F)/(r32R −r32F) = −1.469 (25) r32S/f32 = 0.703 (26) f1A/f1B = 2.756

FIGS. 54A and 54B show various aberrations of the zoom lens systemaccording to Example 14 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 55 shows various aberrations of the zoom lenssystem according to Example 14 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 56A and56B show various aberrations of the zoom lens system according toExample 14 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 14 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 15

FIG. 57 is a diagram showing a sectional view of a zoom lens systemaccording to Example 15 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 57, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingpositive refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with anegative meniscus lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, adouble convex positive lens and a negative meniscus lens having aconcave surface facing to the object.

An aperture stop S is arranged to the object side of the 31 lens groupG31, and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 14 of the third embodiment,vibration reduction coefficient K is 1.16, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.322 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.75, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.440(mm).

Various values associated with Example 15 of the third embodiment of thepresent invention is listed in Table 15. TABLE 15 [Specifications] f =71.40 134.90 294.00 FNO =  4.05  4.29  5.70 2ω = 22.57°  11.76°  5.44°[Lens Data] r d ν n 1 381.8649 3.2698 64.14 1.516330 2 −381.8649 (d2) 371.5714 2.5000 26.52 1.761821 4 49.9993 8.2004 81.54 1.496999 5−1251.0960 (d5) 6 −459.6483 1.4000 49.60 1.772499 7 73.4579 2.3256 8−148.2025 1.4000 49.60 1.772499 9 30.9506 4.0346 23.78 1.846660 10507.9596 2.1322 11 −53.4502 1.4000 49.60 1.772499 12 745.1895 (d12) 13 ∞1.0000 Aperture Stop S 14 299.4180 2.5704 52.64 1.740999 15 −74.38610.2000 16 58.6516 5.0344 81.54 1.496999 17 −40.9400 1.4000 34.971.800999 18 −586.8839 0.2000 19 32.9311 3.0580 60.64 1.603112 20 86.63588.7020 21 66.7204 1.3000 23.78 1.846660 22 34.9761 4.3431 70.23 1.48749023 −113.9382 5.0000 24 249.3959 3.6484 25.42 1.805181 25 −36.8058 1.200039.58 1.804398 26 39.1458 10.9499 27 57.2414 2.6768 31.07 1.688931 28−326.2393 3.9442 29 −22.0804 1.2000 49.60 1.772499 30 −37.9653 (B.f.)Wide-angle end Intermediate Telephoto end [Variable Distances](Infinity) f 71.40016 134.90320 294.00205 d2 14.63133 14.63133 14.63133d5 2.00000 33.48260 46.17223 d12 28.49089 17.74860 0.31866 B.f. 48.7881652.49212 81.78883 [Moving Amount upon Focusing] f 71.40016 134.90320294.00205 δ1B 12.86620 13.12031 13.38598 [Values for ConditionalExpressions] (16) f1/fw = 1.693 (17) f2/fw = −0.410 (18) f3/fw = 0.522(19) f32/f3 = −1.566 (20) f3/f33 = 0.030 (21) n31N − n31P = 0.304 (22)ν31P − ν31N = 46.57 (23) ν32N − ν32P = 14.16 (24) (r32R + r32F)/(r32R −r32F) = −1.372 (25) r32S/f32 = 0.619 (26) f1A/f1B = 2.151

FIGS. 58A and 58B show various aberrations of the zoom lens systemaccording to Example 15 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 59 shows various aberrations of the zoom lenssystem according to Example 15 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 60A and60B show various aberrations of the zoom lens system according toExample 15 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.150,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 15 of the third embodiment shows superb optical performancecorrecting various aberrations.

EXAMPLE 16

FIG. 61 is a diagram showing a sectional view of a zoom lens systemaccording to Example 16 of the third embodiment of the present inventiontogether with a trajectory of each lens group upon zooming.

In FIG. 61, the zoom lens system with a vibration reduction mechanism iscomposed of, in order from an object, a first lens group G1 havingpositive refractive power, a second lens group G2 having negativerefractive power, and a third lens group G3 having positive refractivepower. When the state of lens group positions varies from a wide-angleend state (W) to a telephoto end state (T), the first lens group G1 andthe third lens group G3 move to the object and the second lens group G2moves once to the image I and, then, moves to the object such that adistance between the first lens group G1 and the second lens group G2increases, and a distance between the second lens group G2 and the thirdlens group G3 decreases.

The first lens group G1 is composed of, in order from the object, a 1Alens group G1A having positive refractive power, and a 1B lens group G1Bhaving positive refractive power. The 1A lens group G1A is composed of adouble convex positive lens. The 1B lens group G1B is composed of, inorder from the object, a cemented lens constructed by a negativemeniscus lens having a convex surface facing to the object cemented witha double convex positive lens.

The second lens group G2 is composed of, in order from the object, adouble concave negative lens, a cemented lens constructed by a doubleconcave negative lens cemented with a positive meniscus lens having aconvex surface facing to the object, and a double concave negative lens.

The third lens group G3 is composed of, in order from the object, a 31lens group G31 having positive refractive power, a 32 lens group G32having negative refractive power, and a 33 lens group G33 havingpositive refractive power. The 31 lens group G31 is composed of, inorder from the object, a double convex positive lens, a first cementedlens constructed by a double convex positive lens cemented with anegative meniscus lens, a positive meniscus lens having a convex surfacefacing to the object, and a second cemented lens constructed by anegative meniscus lens having a convex surface facing to the objectcemented with a double convex positive lens. The 32 lens group G32 iscomposed of, in order from the object, a cemented lens constructed by adouble convex positive lens cemented with a double concave negativelens. The 33 lens group G33 is composed of, in order from the object, afixed stop S2, a double convex positive lens and a negative meniscuslens having a concave surface facing to the object.

An aperture stop S is arranged to the object side of the 31 lens groupG31, and is moved together with the third lens group G3 upon zoomingfrom the wide-angle end state (W) to the telephoto end state (T).

Upon detecting a camera shake, vibration reduction on the image plane Iis carried out by moving only the 32 lens group G32 perpendicular to theoptical axis.

Focusing from infinity to a close-range object is carried out by movingthe 1B lens group G1B to the object.

In the wide-angle end state (W) of Example 14 of the third embodiment,vibration reduction coefficient K is 1.25, and the focal length f is71.40 (mm), so that the image rotation of 0.30° can be corrected bymoving the 32 lens group G32 by the amount of 0.299 (mm). In thetelephoto end state (T), vibration reduction coefficient K is 1.90, andthe focal length f is 294.00 (mm), so that the image rotation of 0.15°can be corrected by moving the 32 lens group G32 by the amount of 0.405(mm).

Various values associated with Example 16 of the third embodiment of thepresent invention is listed in Table 16. TABLE 16 [Specifications] f =71.40 135.00 294.00 FNO =  4.05  4.29  5.70 2ω = 22.57°  11.76°  5.44°[Lens Data] r d ν n 1 340.6588 4.2 64.14 1.51633 2 −340.659 (d2) 365.1639 1.8 26.3 1.784696 4 45.8381 8.8 81.61 1.496999 5 −1308.92 (d5) 6−271.25 1.4 49.61 1.772499 7 71.7854 1.3 8 −566.934 1.4 49.61 1.772499 924.4437 4.7 23.78 1.84666 10 133.0962 3.75 11 −46.0918 1.4 49.611.772499 12 1927.614 (d12) 13 ∞ 2 Aperture Stop S 14 188.6747 3.4 60.091.639999 15 −72.245 0.2 16 73.7218 6 81.61 1.496999 17 −38.1983 1.434.96 1.800999 18 −154.661 0.2 19 32.255 4.2 52.42 1.517417 20 143.8547.9 21 333.5741 1.3 23.78 1.84666 22 54.3293 4.1 70.24 1.48749 23−89.5707 10.2 24 256.9205 3.6 25.43 1.805181 25 −35.5686 1.2 39.591.804398 26 35.5686 3.4 27 ∞ 3.1 Fixed Stop S2 28 47.0802 4 34.471.639799 29 −96.8946 2.4 30 −23.3234 1.2 49.61 1.772499 31 −42.5579(B.f.) Wide-angle end Intermediate Telephoto end [Variable Distances](Infinity) f 71.39993 134.99982 294.00047 d2 13.43865 13.43865 13.43865d5 2.49989 31.01849 43.01129 d12 28.21141 18.59271 2.50011 B.f. 53.4000857.30852 87.10064 [Moving Amount upon Focusing] f 71.39991 134.99979294.00046 δ1B 11.08175 11.28593 11.5251 [Values for ConditionalExpression] (16) f1/fw = 1.563 (17) f2/fw = −0.368 (18) f3/fw = 0.525(19) f32/f3 = −1.384 (20) f3/f33 = 0.238 (21) n31N − n31P = 0.304 (22)ν31P − ν31N = 46.57 (23) ν32N − ν32P = 14.16 (24) (r32R + r32F)/(r32R −r32F) = −1.321 (25) r32S/f32 = 0.685 (26) f1A/f1B = 2.051

FIGS. 62A and 62B show various aberrations of the zoom lens systemaccording to Example 16 of the third embodiment in a wide-angle endstate upon focusing at infinity, and meridional lateral aberration atinfinity when vibration reduction is carried out against rotation of0.30°, respectively. FIG. 63 shows various aberrations of the zoom lenssystem according to Example 16 of the third embodiment in anintermediate focal length state upon focusing at infinity. FIGS. 64A and64B show various aberrations of the zoom lens system according toExample 16 of the third embodiment in a telephoto end state uponfocusing at infinity, and meridional lateral aberration at infinity whenvibration reduction is carried out against rotation of 0.15°,respectively.

As is apparent from respective graphs, the zoom lens system according toExample 16 of the third embodiment shows superb optical performancecorrecting various aberrations.

In examples of the third embodiment, although three-group-type zoom lenssystems have been proposed, it is needless to say that a zoom lenssystem merely adding a lens group to the three-group type zoom system iswithin the scope of the present invention. Moreover, in the constructionof each lens group, it is needless to say that a zoom lens system merelyadding a lens element to any one of lens groups of the zoom lens systemaccording to the third embodiment is within the scope of the presentinvention.

Additional advantages and modification will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspect isnot limited to the specific details, and representative devices shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A zoom lens system comprising, in order from an object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; and a third lens group having positiverefractive power, when a state of lens group positions varies from awide-angle end state to a telephoto end state, a distance between thefirst lens group and the second lens group increasing, and a distancebetween the second lens group and the third lens group decreasing, thefirs lens group being composed of, in order from the object, a 1A lensgroup having positive refractive power, and a 1B lens group havingpositive refractive power, focusing from infinity to a close-rangeobject being carried out by moving only the 1B lens group to the object,and the following conditional expressions being satisfied:1.55<f1/fw<2.20−0.55<f2/fw<−0.302.0<f1A/f1B<4.00.16<DAB/fw<0.30 where fw denotes the focal length of the zoom lenssystem in the wide-angle end state, 1 denotes the focal length of thefirst lens group, f2 denotes the focal length of the second lens group,f1A denotes the focal length of the 1A lens group, f1B denotes the focallength of the 1B lens group, and DAB denotes the distance between the 1Alens group and the 1B lens group when the zoom lens system is focused ofinfinity.
 2. The zoom lens system according to claim 1, wherein when thestate of lens group positions varies from the wide-angle end state tothe telephoto end state, the first lens group and the third lens groupmove to the object.
 3. The zoom lens system according to claim 2,further comprising a fourth lens group having negative refractive powerto an image side of the third lens group, wherein when the state of lensgroup positions varies from the wide-angle end state to the telephotoend state, a distance between the third lens group and the fourth lensgroup varies, and the following conditional expressions are satisfied:0.35<f3/fw<0.70−1.50<f4/fw <−0.70−0.10<(D34w−D34t)/fw<0.10 where f3 denotes the focal length of the thirdlens group, f4 denotes the focal length of the fourth lens group, D34wdenotes the distance between the third lens group and the fourth lensgroup in the wide-angle end state, and D34t denotes the distance betweenthe third lens group and the fourth lens group in the telephoto endstate.
 4. The zoom lens system according to claim 3, wherein the 1A lensgroup is composed of only one positive lens, the 1B lens group iscomposed of, in order from the object, a negative meniscus lens having aconvex surface facing to the object, and a positive lens having a convexsurface facing to the object, and the following conditional expressionsare satisfied:50<ν1A35<νν1BP−ν1BN where ν1A denotes Abbe number of the positive lens in the1A lens group at d-line (λ=587.6 nm), ν1BP denotes Abbe number of thepositive lens in the 1B lens group G1B at d-line, and ν1BN denotes Abbenumber of the negative meniscus lens in the 1B lens group G1B at d-line.5. The zoom lens system according to claim 2, wherein the 1A lens groupis composed of only one positive lens, the 1B lens group is composed of,in order from the object, a negative meniscus lens having a convexsurface facing to the object, and a positive lens having a convexsurface facing to the object, and the following conditional expressionsare satisfied:50<ν1A35<ν1BP−ν1BN where ν1A denotes Abbe number of the positive lens in the1A lens group at d-line (λ=587.6 nm), ν1BP denotes Abbe number of thepositive lens in the 1B lens group G1B at d-line, and ν1BN denotes Abbenumber of the negative meniscus lens in the 1B lens group G1B at d-line.6. The zoom lens system according to claim 1, further comprising afourth lens group having negative refractive power to an image side ofthe third lens group, wherein when the state of lens group positionsvaries from the wide-angle end state to the telephoto end state, adistance between the third lens group and the fourth lens group varies,and the following conditional expressions are satisfied:0.35<f3/fw<0.70−1.50<f4/fw<−0.70−0.10<(D34w−D34t)/fw<0.10 where f3 denotes the focal length of the thirdlens group, f4 denotes the focal length of the fourth lens group, D34wdenotes the distance between the third lens group and the fourth lensgroup in the wide-angle end state, and D34t denotes the distance betweenthe third lens group and the fourth lens group in the telephoto endstate.
 7. The zoom lens system according to claim 6, wherein the 1A lensgroup is composed of only one positive lens, the 1B lens group iscomposed of, in order from the object, a negative meniscus lens having aconvex surface facing to the object, and a positive lens having a convexsurface facing to the object, and the following conditional expressionsare satisfied:50<ν1A35<ν1BP−ν1BN where ν1A denotes Abbe number of the positive lens in the1A lens group at d-line (λ=587.6 nm), ν1BP denotes Abbe number of thepositive lens in the 1B lens group G1B at d-line, and ν1BN denotes Abbenumber of the negative meniscus lens in the 1B lens group G1B at d-line.8. The zoom lens system according to claim 1, wherein the 1A lens groupis composed of only one positive lens, the 1B lens group is composed of,in order from the object, a negative meniscus lens having a convexsurface facing to the object, and a positive lens having a convexsurface facing to the object, and the following conditional expressionsare satisfied:50<ν1A35<ν1BP−ν1BN where ν1A denotes Abbe number of the positive lens in the1A lens group at d-line (λ=587.6 nm), ν1BP denotes Abbe number of thepositive lens in the 1B lens group G1B at d-line, and ν1BN denotes Abbenumber of the negative meniscus lens in the 1B lens group G1B at d-line.9. The zoom lens system according to claim 8, wherein the negativemeniscus lens and the positive lens in the 1B lens group are cementedwith each other.
 10. A zoom lens system with a vibration reductionmechanism comprising, in order from an object: a first lens group havingpositive refractive power; a second lens group having negativerefractive power; a third lens group having positive refractive power;and a fourth lens group having negative refractive power, when a stateof lens group positions varies from a wide-angle end state to atelephoto end state, a distance between the first lens group and thesecond lens group increasing, a distance between the second lens groupand the third lens group decreasing, and a distance between the thirdlens group and the fourth lens group varying, the fourth lens groupbeing composed of, in order from the object, a 41 lens group, a 42 lensgroup having negative refractive power, and a 43 lens group, at leastone of the 41 lens group and the 43 lens group having positiverefractive power, and image blur on an image plane caused by a camerashake being reduced by moving only the 42 lens group perpendicular tothe optical axis.
 11. The zoom lens system with a vibration reductionmechanism according to claim 10, wherein the following conditionalexpression is satisfied:0.10<f42/f4<0.90 where f4 denotes the focal length of the fourth lensgroup, and f42 denotes the focal length of the 42 lens group.
 12. Thezoom lens system with a vibration reduction mechanism according to claim11, wherein the following conditional expressions are satisfied:−2.10<f4/fw<−0.70−2.10<(1/f41+1/f43)·f4<−0.40 where fw denotes the focal length of thezoom lens system in the wide-angle end state, f41 denotes the focallength of the 41 lens group and f43 denotes the focal length of the 43lens group.
 13. The zoom lens system with a vibration reductionmechanism according to claim 10, wherein when the state of lens grouppositions varies from the wide-angle end state to the telephoto endstate, the first lens group, the third lens group, and the fourth lensgroup move to the object.
 14. The zoom lens system with a vibrationreduction mechanism according to claim 10, wherein the 41 lens groupincludes at least one positive lens, the 42 lens group includes at leastone positive lens and at least one negative lens, and the 43 lens groupincludes at least one positive lens.
 15. The zoom lens system with avibration reduction mechanism according to claim 14, wherein the 41 lensgroup includes, in order from the object, a negative lens having aconcave surface facing to the image, and a positive lens having a convexsurface facing to the object, and the following conditional expressionis satisfied:0.20<n41N−n41P where n41N denotes refractive index of the negative lensin the 41 lens group at d-line (λ=587.6 nm), and n41P denotes refractiveindex of the positive lens in the 41 lens group at d-line.
 16. The zoomlens system with a vibration reduction mechanism according to claim 14,wherein the 42 lens group includes, in order from the object, a positivelens having a convex surface facing to the image, and a double concavenegative lens, and the following conditional expression is satisfied:10.0<ν42N−ν42P where ν42N denotes Abbe number of the double concavenegative lens in the 42 lens group at d-line (λ=587.6 nm), and ν42Pdenotes Abbe dumber of the positive lens in the 42 lens group at d-line.17. A zoom lens system with a vibration reduction mechanism comprising,in order from an object: a first lens group having positive refractivepower; a second lens group having negative refractive power; and a thirdlens group having positive refractive power, when a state of lens grouppositions varies from a wide-angle end state to a telephoto end state, adistance between the first lens group and the second lens groupincreasing, and a distance between the second lens group and the thirdlens group decreasing, the third lens group being composed of, in orderfrom the object, a 31 lens group having positive refractive power, a 32lens group having negative refractive power, and a 33 lens group, andimage blur on an image plane caused by a camera shake being reduced bymoving only the 32 lens group perpendicular to the optical axis.
 18. Thezoom lens system with a vibration reduction mechanism according to claim17, wherein the following conditional expressions are satisfied:1.40<f1/fw<2.00−0.53<f2/fw<−0.320.35<f3/fw<0.65−2.00<f32/f3<−0.80−0.20<f3/f33<0.50 where fw denotes the focal length of the zoom lenssystem in the wide-angle end state, f1 denotes the focal length of thefirst lens group, f2 denotes the focal length of the second lens group,f3 denotes the focal length of the third lens group, f32 denotes thefocal length of the 32 lens group, and f33 denotes the focal length ofthe 33 lens group.
 19. The zoom lens system with a vibration reductionmechanism according to claim 17, wherein when the state of lens grouppositions varies from the wide-angle end state to the telephoto endstate, the first lens group and the third lens group move to the object.20. The zoom lens system with a vibration reduction mechanism accordingto claim 17, wherein the 31 lens group includes at least three positivelenses and at least one negative lens, the 32 lens group includes atleast one positive lens and at least one negative lens, and the 33 lensgroup includes at least one positive lens and at least one negativelens.
 21. The zoom lens system with a vibration reduction mechanismaccording to claim 17, wherein the 31 lens group includes, in order fromthe object, a double convex positive lens, a first cemented lensconstructed by a double convex positive lens cemented with a negativelens having a concave surface facing to the object, a positive meniscuslens having a convex surface facing to the object, and a second cementedlens, and the following conditional expressions are satisfied:0.20<n31N−n31P30.0<ν31P−ν31N where n31N denotes refractive index of the negative lensin the first cemented lens at d-line (λ=587.6 nm), n31P denotesrefractive index of the positive lens in the first cemented lens atd-line, ν31N denotes Abbe number of the negative lens in the firstcemented lens at d-line, and ν31P denotes Abbe number of the positivelens in the first cemented lens at d-line.
 22. The zoom lens system witha vibration reduction mechanism according to claim 17, wherein the 32lens group includes, in order from the object, a positive lens having aconvex surface facing to the image, and a double concave negative lens,and the following conditional expression is satisfied:10.0<ν32N−ν32P where ν32N denotes Abbe number of the double concavenegative lens in the 32 lens group at d-line (λ=587.6 nm), and ν32Pdenotes Abbe number of the positive lens in the 32 lens group at d-line.23. The zoom lens system with a vibration reduction mechanism accordingto claim 17, wherein the 32 lens group is composed of, in order from theobject, a cemented lens constructed by a positive lens having a convexsurface facing to the image cemented with a double concave negativelens, and the following conditional expression is satisfied:−2.00<(r32R+r32F)/(r32R−r32F)<−0.70 where r32F denotes the radius ofcurvature of the object side surface of the positive lens in the 32 lensgroup, r32R denotes the radius of curvature of the image side surface ofthe double concave negative lens in the 32 lens group.
 24. The zoom lenssystem with a vibration reduction mechanism according to claim 23,wherein the following conditional expression is satisfied:0.40<r32S/f32<0.90 where r32S denotes the radius of curvature of thecemented lens in the 32 lens group, and f32 denotes the focal length ofthe 32 lens group.
 25. The zoom lens system with a vibration reductionmechanism according to claim 17, wherein the first lens group iscomposed of, in order from the object, a 1A lens group having positiverefractive power, and a 1B lens group having positive refractive power,focusing from infinity to a close-range object is carried out by movingonly the 1B lens group to the object, and the following conditionalexpression is satisfied:1.70<f1A/f1B<4.00 where f1A denotes the focal length of the 1A lensgroup and f1B denotes the focal length of the 1B lens group.